Battery having electrolyte with mixed solvent

ABSTRACT

The battery includes an electrolyte activating one or more cathodes and one or more anodes. The electrolyte includes one or more salts in a solvent. The solvent includes one or more organic solvents and one or more silanes and/or one or more siloxanes.

REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.11/346,087, filed on Feb. 2, 2006, entitled “Battery Having Electrolytewith Mixed Solvent”; and this application is a continuation-in-part ofU.S. patent application Ser. No. 11/056,866, filed on Feb. 10, 2005,entitled “Electrochemical Device Having Electrolyte IncludingDisiloxane;” and this application is a continuation-in-part of U.S.patent application Ser. No. 11/056,867, filed on Feb. 10, 2005, entitled“Electrochemical Device Having Electrolyte Including Trisiloxane;” andthis application is a continuation-in-part of U.S. patent applicationSer. No. 11/056,868, filed on Feb. 10, 2005, entitled “ElectrochemicalDevice Having Electrolyte Including Tetrasiloxane;” and this applicationis a continuation-in-part of U.S. patent application Ser. No.11/056,869, filed on Feb. 10, 2005, entitled “Electrolyte IncludingSilane for use in Electrochemical Devices;” which is acontinuation-in-part of U.S. patent application Ser. No. 11/053,338,filed on Feb. 8, 2005, entitled “Reduction of Impurities in BatteryElectrolyte;” and this application is also a continuation-in-part ofU.S. patent application Ser. No. 10/971,912, filed on Oct. 21, 2004,entitled “Battery Having Electrolyte Including Organoborate Salt;” andthis application is a continuation-in-part of U.S. patent applicationSer. No. 11/211,970, filed on Aug. 24, 2005, entitled “Battery HavingElectrolyte Including Substituted Borane Additive;” and this applicationis a continuation-in-part of U.S. patent application Ser. No.11/271,473, filed on Nov. 10, 2005, entitled “Flame Retardant Battery;”and this application is a continuation-in-part of U.S. patentapplication Ser. No. 11/272,261, filed on Nov. 10, 2005, entitled “FlameRetardant Battery;” and this application is a continuation-in-part ofU.S. patent application Ser. No. 11/072,739, filed on Mar. 3, 2005,entitled “Battery Having Enhanced Energy Density;” which is acontinuation-in-part of U.S. patent application Ser. No. 10/962,125,filed on Oct. 7, 2004, and entitled “Battery Having ElectrolyteIncluding One or More Additives;” which is a continuation-in-part ofU.S. patent application Ser. No. 10/496,231, filed on May 20, 2004,entitled “Method for Fabricating Composite Electrodes;” which claimspriority to PCT Application number PCT/US03/08783, filed on Mar. 20,2003, entitled “Method for Fabricating Composite Electrodes;” and thisapplication claims the benefit of U.S. Provisional Patent ApplicationSer. No. 60/668,878, filed on Apr. 5, 2005, entitled “Flame RetardantBattery;” each of which is incorporated herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under W15P7T-05-C-R403awarded by U.S. Army Communications-Electronic Research & EngineeringCenter. The government may have certain rights in the invention.

FIELD

The present invention relates to electrochemical devices, and moreparticularly to electrolytes for use in electrochemical devices.

BACKGROUND

Recent improvements in portable electronic devices have increased thedemand for batteries with a high energy density in order to increase thelongevity of these devices. A variety of lithium secondary batterieshave been studied to meet these demands. Many of these batteries haveexplored the use of lithium metal anodes and carbonaceous anodes.Theoretical calculations show that lithium metal may be able to providea higher energy density than a carbonaceous anode.

Batteries having lithium metal anodes are difficult to commercializebecause they generate dendritic lithium on the surface of the lithiummetal during charge and discharge cycle. The dendritic lithium can growtoward the cathode through the separator and cause an internal short inthe battery. This short can result in a dangerous release of heat.Additionally, current can concentrate on the dendrites causing alocalized deposition of lithium on the anode. This localized depositioncan reduce the cycling efficiency of the battery.

Further, lithium metal anodes can reduce the cycling performance of abattery. Conventional organic electrolytes in contact with lithium metalget reduced and can form a passivation layer on the anode. When otheranode materials are employed, the formation of the passivation layerstops or slows when the surface of the active material is covered by astable passivation layer. However, the growth of the dendritic lithiumpermits the passivation layer to continue forming and increases thesurface area over which the passivation layer must be formed. Thecontinued formation of the passivation layer reduces the battery'scoulombic efficiency and can accelerate electrolyte degradation. Thereis a need for a secondary battery that can take advantage of lithiummetal anodes.

SUMMARY

The battery includes an electrolyte activating one or more anodes andone or more cathodes. The electrolyte includes one or more salts in asolvent. The solvent includes one or more organic solvents and one ormore components selected from a group consisting of silanes andsiloxanes. At least one of the anodes includes or consists of one ormore components selected from the group consisting of lithium metal,lithium metal alloy and lithium metal intermetallic compound.

A method of generating an electrochemical device is also disclosed. Themethod includes activating one or more anodes and one or more cathodeswith an electrolyte. The electrolyte includes one or more salts in asolvent. The solvent includes one or more organic solvents and one ormore components selected from a group consisting of silanes andsiloxanes. At least one of the anodes includes or consists of one ormore components selected from the group consisting of lithium metal,lithium metal alloy and lithium metal intermetallic compound.

The siloxanes can include one or more silicons linked to a substituentthat includes a poly(alkylene oxide) moiety or a cyclic carbonatemoiety. The siloxane can be a polysiloxane, tetrasiloxane, a trisiloxaneor a disiloxanes. The silanes can include a silicon linked to one ormore substituents that each include a poly(alkylene oxide) moiety or acyclic carbonate moiety. In some instances, at least one of the one ormore organic solvents can selected from a group consisting of cycliccarbonates, linear carbonates, dialkyl carbonates, aliphatic carboxylateesters, linear ethers, cyclic ethers, and fluorinated carboxylateesters.

The one or more salts can be an organoborate salt such as an aromaticbis[chelato]borate or a nonaromatic bis[chelato]borate. In someinstance, the organoborate is selected from a group consisting ofbis[benzenediolato (2-)-O,O′]borate, bis[substituted benzenediolato(2-)-O,O′]borate, bis[salicylato]borate, bis[substitutedsalicylato]borate, bis[2,2′-biphenyldiolato(O,O′)]borate,bis[substituted 2,2′-biphenyldiolato(O,O′)]borate),bis[oxalato(2-)-O,O′]borate, bis[malonato(2-)-O,O′]borate,bis[succinato]borate, [.alpha.-hydroxy-carboxylato]borate,[.alpha.-hydroxy-carboxylato]borate, [.beta.-hydroxy-carboxylato]borate,[.beta.-hydroxy-carboxylato]borate, [.alpha.-dicarboxylato]borate, and[.alpha.-dicarboxylato]borate. In some instances, the organoborate saltis a lithium organoborate salt. In one example, the organoborate saltincludes lithium bis-oxalato borate (LiBOB) or lithium difluorooxalatoborate (LiDfOB).

The organoborate salt can be represented by the following formula:

wherein M⁺ is a metal ion selected from the Group I or Group II elementsin the periodic table; Y₁ and Y₂ are each selected from the groupconsisting of: —CX(CR₂)_(a)CX—, —CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—,—SO₂(CR₂)_(b)SO₂—, and —CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl,halogenated alkyl, —C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; R′ is halogen or hydrogen; R is hydrogen, alkyl,halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to 4.

The organoborate salt can be represented by the following formula:

wherein M⁺ is a metal ion selected from the Group I or Group IIelements; Y₃ is selected from the group consisting of —CX(CR₂)_(a)CX—,—CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—, —SO₂(CR₂)_(b)SO₂—, and—CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl, —C═NR′, CR′₃ or R′;R″ is a halogen; R′ is halogen or hydrogen; R is hydrogen, alkyl,halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to 4.

In addition to organoborate salts or as an alternative to organoboratesalts, the one or more non-organoborate salts selected from a groupconsisting of LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiSbF₆, LiCF₃SO₃, LiC₆F₅SO₃,LiC(CF₃SO₂)₃, LiN(SO₂C₂F₅)₂, LiN(SO₂CF₃)₂, LiAlCl₄, LiGaCl₄, LiSCN,LiO₂, LiO₃SCF₃, LiO₂CCF₃, LiSO₆F, LiB(C₆H₅)₄, Li-methide, Li-imide andlithium alkyl fluorophosphates.

The battery can include one or more cathodes that each include,fluorinated carbon (CF_(x)), lithium vanadium oxide such as the lithiumvanadium oxide represented by Li_(1+y)V₃O₈, polypyrrole, H₂V₃O₈, metalvanadium oxides represented by M_(z)H_(1-z)V₃O₈, CuCl₂, silver vanadiumoxides such as Ag₂V₄O₁₁, LiCuCl₂, TiS₂, MoO₂, MoS₂, MnO₂, V₂O₅, V₆O₁₃,H₂V₃O₈, LiCoO₂, LiNiO₂, LiFePO₄, LiMnO₂, LiCoNiMnO₂, LiCoNiM′O₂, andcombinations thereof. In some instances, the cathode active materialsinclude or consist of one or more active materials.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of a battery.

FIG. 2 illustrates a cross section of a button cell.

FIG. 3 compares the cycling performance of batteries having anelectrolyte that includes a mixture of siloxane and organic solventagainst the performance of a battery having only organic solvents.

DESCRIPTION

A battery employing an anode that includes lithium metal is disclosed.The battery employs an electrolyte that includes one or more salts in asolvent. The solvent includes one or more organic solvents and one ormore silicon based solvents selected from a group consisting of silanesand siloxanes. When this solvent is employed in a secondary battery, thesolvent has been provided surprising cycling performance. For instance,the battery disclosed in Example 1 has a discharge capacity retention ofabout 100% even after 108 cycles. The passivation layer that resultsfrom this solvent has been studied and shown to be compact andhomogenous. Additionally, this passivation layer appears to preventadditional consumption of the lithium metal. The passivation layersformed from conventional electrolytes that include only organic solventsare often porous and weak after cycling. The features are characteristicof a high surface area cause by heavy dendrite formation on the surfaceof lithium metals. In contrast, the passivation layer formed from thecurrent electrolyte appears to be appears to be denser, stronger, andshow fewer dendrites after cycling illustrating a more stablepassivation layer. Without being bound to theory, it is believed thatthese features of the passivation layer are the source of the improvedcycling performance that results from the disclosed electrolytes.

The solvent can include polysiloxanes but preferably includes orconsists of tetrasiloxanes, trisiloxanes and/or disiloxanes.Tetrasiloxanes, trisiloxanes or disiloxanes can yield an electrolytewith a lower viscosity than electrolytes that include similarlystructured polysiloxanes. The reduced viscosity can increase theconductivity of the electrolyte and can improve wetting of electrodes inan electrochemical device enough to enhance the homogeneity of theelectrolyte distribution in the cell. The enhanced homogeneity can besufficient to increase the capacity and cycling properties of batteries.Accordingly, the cycling performance of the battery can be enhanced bythe siloxanes in the solvent and by the passivation layer stability.

The solvent can also include or consist of one or more silanes. Silanescan have a viscosity that is reduced even relative to similarlystructured polysiloxanes, tetrasiloxanes, trisiloxanes or disiloxanes.The additional reduction in viscosity can further increase theconductivity of the electrolyte and improve wetting of electrodes in anelectrochemical device enough to further increase the capacity andcycling properties of batteries. Accordingly, the cycling performance ofthe battery can be enhanced by both the silanes in the solvent and bythe passivation layer stability.

The tetrasiloxanes, trisiloxanes, disiloxanes and/or silanes can alsoprovide an electrolyte with high ionic conductivities in addition toenhanced cycling properties. For instance, one or more of the siliconsin the tetrasiloxanes, trisiloxanes, disiloxanes and/or silanes can eachbe linked to a first substituent that includes a poly(alkylene oxide)moiety. The poly(alkylene oxide) moieties can help dissolve lithiumsalts employed in the electrolyte. Accordingly, the tetrasiloxanes,trisiloxanes, disiloxanes and/or silanes can provide an electrolyte witha concentration of free ions suitable for use in batteries.Additionally, the poly(alkylene oxide) moieties can enhance the ionicconductivity of the electrolyte at room temperatures. For instance,these siloxanes and/or silanes can yield an electrolyte with an ionicconductivity higher than 1×10⁻⁴ S/cm at 25° C. or higher than 3×10⁻⁴S/cm at 37° C. At these performance levels, the electrolytes can besuitable for use in batteries such as high-energy and long cycle lifelithium secondary batteries, satellite applications, and biomedicaldevices such as defibrillators.

The presence of the organic solvents in the electrolyte can furtherreduce the viscosity of the siloxanes and/or the silanes. Additionallyor alternately, the addition of organic salts can increase the ionicconductivity of the electrolyte. Examples of suitable organic solventsinclude, but are not limited to, cyclic carbonates, linear carbonates,dialkyl carbonates, aliphatic carboxylate esters, gamma.-lactones,linear ethers, cyclic ethers, aprotic organic solvents, and fluorinatedcarboxylate esters. In some instances, the solvent excludes organicsolvents. In some instances, the solvent excludes siloxanes and silanes.A suitable volume ratio of the total organic solvents to the totalsiloxane and silane is greater than 1:4, or 3:7 and/or less than 2:1.The volume ratio is preferably less than 1:4 or 1:1.

FIG. 1 is a schematic view of a suitable battery 22. The battery 22includes an electrolyte 40 activating a cathode 42 and an anode 44. Aseparator 46 separates the cathode 42 and anode 44. The cathode 42includes a cathode medium 48 on a cathode substrate 50. The anode 44includes an anode medium 52 on an anode substrate 54. Although thebattery is illustrated as including one anode and one cathode, thebattery can include more than one anode and/or more than one cathodewith the anodes and cathodes each separated by a separator.Additionally, the battery can have a variety of different configurationssuch as stacked configuration, a “jellyroll” or wound configurations. Insome instances, the battery is hermetically sealed. Hermetic sealing canreduce entry of impurities into the battery. As a result, hermeticsealing can reduce active material degradation reactions due toimpurities. The reduction in impurity induced lithium consumption canstabilize battery capacity.

Suitable cathode substrates 50 include, but are not limited to,aluminum, stainless steel, titanium, or nickel substrates. An example ofa cathode substrate that can enhance conductivity is a carbon coatedaluminum current collector. The carbon coating may be applied using anysuitable process known in the art, such as by coating a paste made ofcarbon and a binder. The thickness of the carbon coating can be lessthan 15 microns, less than 10 microns, about 3 microns or less, and lessthan 2 microns.

The cathode medium 48 includes or consists of one or more cathode activematerials. Suitable cathode active materials include, but are notlimited to, Li_(x)VO_(y), LiCoO₂, LiNiO₂,LiM_(1-x′)Co_(y′)Me_(z′)O₂LiMn_(0.5)Ni_(0.5)O₂,LiMn_((1/3))Co_((1/3))Ni_((1/3))O₂, LiFePO₄, LiMn₂O₄, LiFeO₂,LiMc_(0.5)Mn_(1.5)O₄, LiMn_(1.5)McO₄, vanadium oxide, lithium vanadiumoxides, carbon fluoride (CFO and mixtures thereof wherein Me is Al, Mg,Ti, B, Ga, Si, Mn, Zn, Mo, Nb, V and Ag and combinations thereof, andwherein Mc is a divalent metal such as Ni, Co, Fe, Cr, Cu, andcombinations thereof. In some instances, x is ≧⅓ before initialdischarge of the battery and/or y is in a range of 7/3 to 3 beforeinitial discharge of the battery and/or x′ is ≧0 before initialdischarge of the battery and/or 1−x′+y′+z′=1 and/or x″ is ≧0 or x″is >0.2 before initial discharge of the battery. Example cathodematerials include one or more lithium transition metal oxides selectedfrom the group consisting of Li_(x)VO_(y) such as LiV₃O₈, and LiV₆O₁₈,LiCoO₂, LiNiO₂, LiNi_(1-x)Co_(y)Me_(z)O₂, LiMn_(0.5)Ni_(0.5)O₂,LiMn_(0.3)Co_(0.3)Ni_(0.3)O₂, LiFePO₄, LiMn₂O₄, LiFeO₂,LiMc_(0.5)Mn_(1.5)O₄, and LiMnO₂.

The cathode medium 48 can optionally include binders and/or conductorssuch as PVDF, graphite and acetylene black in addition to the one ormore cathode active materials. Suitable binders include, but are notlimited to, PVdF, fluoropolymer, polytetrafluoroethylene orpolyvinylidene fluoride present at about 1 to about 5 weight percent ofthe cathode active material, and styrene butadiene rubber (SBR).Suitable conductors and/or diluents include, but are not limited to,acetylene black, carbon black and/or graphite or metallic powders suchas powdered nickel, aluminum, titanium and stainless steel.

A suitable material for the anode substrate 54 includes, but is notlimited to, titanium, a titanium alloy, stainless steel, nickel, copper,tungsten, tantalum and alloys thereof.

The anode medium 52 includes or consists of one or more componentsselected from the groups consisting of lithium metal, lithium metalalloys, and lithium intermetallic compounds. The anode active materialcan include one or more layers of a material that includes lithium andone or more layers of other anode materials. Suitable lithium metalalloys can be a substitutional alloy or an interstitial alloy. Examplesof suitable alloys include, but are not limited to, Li—Si, Li—B,Li—Si—B, Li—Al. Another example of a suitable lithium alloy is alithium-aluminum alloy. However, increasing the amounts of aluminumpresent in the alloy can reduce the energy density of the cell. Examplesof suitable intermetallic compounds include, but are not limited to,intermetallic compounds that include lithium metal and one or morecomponents selected from the group consisting of Ti, Cu, Sb, Mn, Al, Ge,Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn and La. In someinstances, the anode active material consists of lithium metal. Further,the anode active medium can serve as both the anode active medium and asthe anode substrate. For instance, the anode can consist of lithiummetal. The reaction potential for lithium metals to give up electrons isgenerally less than 1V versus Li/Li⁺ equilibrium potential. In instanceswhere the anode includes a substrate, suitable methods for placing theanode active material on the anode substrate include, but are notlimited to, lamination, deposition, sputtering, or dipping.

In some instances, the anode consists of the anode medium. Accordingly,the anode medium also serves as the anode substrate. For instance, theanode can consist of lithium metal.

Suitable separators 46 include, but are not limited to, polyolefins suchas polyethylene. Illustrative separator materials also include fabricswoven from fluoropolymeric fibers including polyvinylidine fluoride,polyethylenetetrafluoroethylene, and polyethylenechlorotrifluoroethyleneused either alone or laminated with a fluoropolymeric microporous film,non-woven glass, polypropylene, polyethylene, glass fiber materials,ceramics, polytetrafluoroethylene membrane commercially available underthe designation ZITEX (Chemplast Inc.), polypropylene/polyethylenemembrane commercially available under the designation CELGARD (CelanesePlastic Company, Inc.), a membrane commercially available under thedesignation DEXIGLAS (C. H. Dexter, Div., Dexter Corp.), and apolyethylene membrane commercially available from Tonen Chemical Corp.

The electrolyte includes one or more salts in a solvent. The one or moresalts can include or consist of an organoborate salts. Suitableorganoborate salts include lithium organoborate salt. The organoboratesalt can be a bis[bidentate]borate, also known as a bis[chelato]borate.Suitable bis[bidentate]borates include aromatic bis[bidentate]boratessuch as bis[benzenediolato (2-)-O,O′]borate, bis[substitutedbenzenediolato (2-)-O,O′]borate, bis[salicylato]borate, bis[substitutedsalicylato]borate, bis[2,2′-biphenyldiolato(O,O′)]borate, andbis[substituted 2,2′-biphenyldiolato(O,O′)]borate]. In some instances,the organoborate salt is a nonaromatic bis[bidentate]borate, such asbis[oxalato (2-)-O,O′]borate, bis[malonato (2-)-O,O′]borate,bis[succinato]borate, [.alpha.-hydroxy-carboxylato]borate,[.alpha.-hydroxy-carboxylato]borate, [.beta.-hydroxy-carboxylato]borate,[.beta.-hydroxy-carboxylato]borate, [.alpha.-dicarboxylato]borate, and[.alpha.-dicarboxylato]borate. Examples of lithium bis(bidentate) saltsinclude lithium bis(tetrafluoroethylenediolato)borate LiB(OCF₂CF₂O)₂,lithium bis(hexafluoropropylenediolato)borate LiB[OCF(CF₃)CF₂O]₂ andlithium bis[1,2-tetrakis(trifluoromethyl)ethylenedialato(2-)O,O-′]borateor lithium bis(perfluoropinacolato)borate LiB[OC(CF₃)₂C(CF₃)₂O]₂. Apreferred lithium bis(bidentate) salt is lithium bis-oxalato borate(LiBOB).

One example of the organoborate salt includes: a boron linked directlyto at least two oxygens and an organic moiety linking two of theoxygens. In some instances, the boron is also linked directly to twohalogens. Another example of the organoborate salt includes: a boronlinked directly to each of four oxygens; a first organic moiety linkingtwo of the oxygens; and a second organic moiety linking the other twooxygens. The first organic moiety and the second organic moiety can bethe same or different. The first organic moiety and/or the secondorganic moiety can be: substituted or unsubstituted; and/or branched orunbranched; and/or saturated or unsaturated. The backbone of an organicmoieties extending between the boron linked oxygens can include onlycarbons or can include carbons and one or more oxygens. In someinstances, one or both of the organic moieties are halogenated. In oneexample, the first organic moiety and/or the second organic moiety isfluorinated.

An example of the organoborate salt is represented by the followingFormula I-A:

wherein M⁺ is a metal ion selected from the Group I or Group IIelements; Y₁ and Y₂ are each selected from the group consisting ps of—CX(CR₂)_(a)CX—, —CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—,—SO₂(CR₂)_(b)SO₂—, and —CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl,halogenated alkyl, —C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; R′ is halogen or hydrogen; R is hydrogen, alkyl,halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to 4. M⁺ ispreferably selected from Group I and is most preferably lithium. Y₁ andY₂ can be the same or different. Z and Z′ can be the same or different.The R′ can be the same or different and the R can be the same ordifferent.

In an example of an organoborate salt according to Formula I-A, Y₁ andY₂ are each —CX(CR₂)_(a)CX—; each X is ═O and each R is hydrogen. Inanother example of the organoborate salt, Y₁ and Y₂ are each—CX(CR₂)_(a)CX—; each X is ═O and each R is a halogen. In anotherexample of the organoborate salt, Y₁ and Y₂ are each —CX(CR₂)_(a)CX—;each X is ═O and each R is fluoro.

In a preferred example of an organoborate salt according to Formula I-A,Y₁ and Y₂ are each —CZZ′(CR₂)_(a)CZZ′—; each of the R′ is hydrogen andeach of the R are hydrogen. In another preferred example, Y₁ and Y₂ areeach —CZZ′(CR₂)_(a)CZZ′—; each of the R′ is halogen and each of the Rare halogens. In another preferred example, Y₁ and Y₂ are each—CZZ′(CR₂)_(a)CZZ′—; each of the R′ is fluorine and each of the R arefluorine.

Other suitable organoborate salts for use with the battery includemono[bidentate]borates. For instance, the salt can be a dihalomono[bidentate]borate such as a dihalo oxalato borate. An example of adihalo oxalato borate is a difluoro oxalato borate. The organoboratesalts can be lithium organoborate salts such as lithiummono[bidentate]borate. For instance, the salt can be a lithium dihalomono[bidentate]borate such as a lithium dihalo oxalato borate. Apreferred lithium dihalo oxalato borate is a lithium difluoro oxalatoborate (LiDfOB).

The organoborate salt can include a boron linked directly to twohalogens and also linked directly to two oxygens that are linked to oneanother by an organic moiety. The organic moiety and/or the secondorganic moiety can be: substituted or unsubstituted; and/or branched orunbranched; and/or saturated or unsaturated. The backbone of the organicmoiety can include only carbons or can include carbons and one or moreoxygens. In some instances, the organic moiety is completely orpartially halogenated. In one example, the organic moiety isfluorinated.

An example of the organoborate salt is represented by the followingFormula I-B:

wherein M⁺ is a metal ion selected from the Group I or Group IIelements; Y₃ is selected from the group consistingof —CX(CR₂)_(a)CX—, —CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—,—SO₂(CR₂)_(b)SO₂—, and —CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl,halogenated alkyl, —C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; R″ is a halogen; R′ is halogen or hydrogen; R ishydrogen; alkyl, halogenated alkyl, cyano, or halogen; a is 0 to 4 and bis 1 to 4. M⁺ is preferably selected from Group I and is most preferablylithium. Z and Z′ can be the same or different. The R″ can be the sameor different. The R′ can be the same or different. The R can be the sameor different.

In an example of an organoborate salt according to Formula I-B, Y₃ is—CX(CR₂)_(a)CX—; each X is ═O and each R″ is a halogen. In anotherexample of the organoborate salt, Y₃ is —CX(CR₂)_(a)CX— and each R″ is afluorine.

In some instances, the organoborate salt is a tridentate borate such asa lithium tridentate borate. Alternately, the organoborate salt can be atetradentate borate such as lithium tetradentate borate. An examplelithium tetradentate borate includes LiB[OC(CF₃)₂]₄.

Examples of organoborate salts are disclosed in U.S. Provisional PatentApplication Ser. No. 60/565,211, filed on Apr. 22, 2004, entitled“Organoborate Salt in Electrochemical Device Electrolytes,” andincorporated herein in its entirety; and in U.S. Provisional PatentApplication Ser. No. 60/563,850, filed on Apr. 19, 2004, entitled“Organoborate Salt in Electrochemical Device Electrolytes,” andincorporated herein in its entirety; and in U.S. Provisional PatentApplication Ser. No. 60/563,848, filed on Apr. 19, 2004, entitled“Composition Check for Organoborate Salt Employed in ElectrochemicalDevice Electrolytes,” and incorporated herein in its entirety.

The electrolyte can include one or more salts in addition to the one ormore organoborate salts or as an alternative to the one or moreorganoborate salts. Suitable salts for use with the electrolyte include,but are not limited to, alkali metal salts including lithium salts.Examples of lithium salts include LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiSbF₆,LiCF₃SO₃, LiC₆F₅SO₃, LiC₄F₉CO₂, LiC(CF₃SO₂)₃, LiN(SO₂C₂F₅)₂,LiN(SO₂CF₃)₂, LiAlCl₄, LiGaCl₄, LiSCN, LiO₂, LiO₃SCF₃, LiO₂CCF₃, LiSO₆F,LiB(C₆H₅)₄, LiB₁₀Cl₁₀, lithium lower aliphatic carboxylate, chloroboranlithium, lithium tetraphenylborate, LiBr, LiI, LiSCN, LiCl, imides,Li-methide, Li-imide, lithium alkyl fluorophosphates and mixturesthereof. In some instances, the electrolyte includes one or more ofthese salts and excludes organoborate salts.

In some instances, the electrolyte is prepared such that the totalconcentration of the one or more salts in the electrolytes is about 0.1to 2.0 M, about 0.5 to 1.5 M, or about 0.7 to 1.2 M. In some instances,the one or more organoborate salts are preferably present in theelectrolyte at a concentration of about 0.1 to 2.0 M, about 0.5 to 1.5M, or about 0.7 to 1.2 M. In some instances, the one or moreorganoborate salts are present in a concentration less than 1.5 M, orless than 0.1M, or less than 0.05 M and other salts are present in theelectrolyte.

The solvent can include or consist of one or more polysiloxanes having abackbone with five or more silicons. One or more of the silicons can belinked to a first substituent and/or to a second substituent. The firstsubstituent includes a poly(alkylene oxide) moiety and the secondsubstituent includes a cyclic carbonate moiety. Suitable firstsubstituents include side chains or cross links to other polysiloxanes.Further, each of the first substituents can be the same or different. Inone example of the polysiloxane, each of the first substituents is aside chain. Suitable second substituents include side chains. Further,each of the second substituents can be the same or different. Each ofthe second substituents can be the same or different. In some instances,the terminal silicons in the backbone are not linked to either a firstsubstituent or a second substituent. Each of the non-terminal siliconscan be linked to at least one first substituent or to at least onesecond substituent. In some instances, the polysiloxane excludes secondsubstituents. One or more of the silicons in the backbone of thepolysiloxane can be linked to a cross-link to another polysiloxane. Thecross-link can include a poly(alkylene oxide) moiety. Examples ofsuitable polysiloxanes are disclosed in U.S. patent application Ser. No.10/810,019, filed on Mar. 25, 2004, entitled “Polysiloxane for Use inElectrochemical Cells,” and incorporated herein in its entirety.

Examples of suitable polysiloxanes have a structure according to GeneralFormula II:

where R is alkyl or aryl; R₁ is alkyl or aryl; R₃ is represented by:

R₄ is a cross link that links the polysiloxane backbone to anotherpolysiloxane backbone; R₅ is represented by:

R₆ is represented by:

R₇ is hydrogen; alkyl or aryl; R₈ is alkyl or aryl; R₉ is oxygen or anorganic spacer; R₁₀ is an oxygen or an organic spacer; k is 0 or greaterthan 0; p is 3, greater than 3 and/or less than 20; q is 1 to 2; m is 0or greater than 0 and n is 0 or greater than 0 and can be 2 to 25. Insome instances, n+m+k is 3 or greater than 3. In some instances, m isgreater than 0 and a ratio of n:m is 1:1 to 100:1 and is more preferably5:1 to 100:1. One or more of the alkyl and/or aryl groups can besubstituted, unsubstituted, halogenated, and/or fluorinated. A suitableorganic spacer can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide, or bivalent ethermoiety. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₉ is represented by: —O—(CH₂)₃—O— or —(CH₂)₃—O— with theoxygen linked to the polyethylene oxide moiety. In another example, R₁₀is represented by: —CH₂—O—(CH₂)₃— where the single —CH₂— group ispositioned between the carbonate and the oxygen or —CH₂—O—.

In instances, where a polysiloxane according to Formula II includes oneor more cross links, a suitable ratio for (number of cross links):(m+n)includes, but is not limited to, a ratio in a range of 1:4 to 1:200, ina range of 1:6 to 1:100, or in a range of 1:6 to 1:70.

Each of the R₃ can be the same or different. In some instances, one ofthe R₃ includes a poly(alkylene oxide) moiety and another R₃ includes acyclic carbonate moiety. The structures of R₃ can be the same as thestructure of R₅. In some instances, the R₃ structures are different fromthe R₅ structures. When m is greater than 0, the structures of R₃ can bethe same as the structure of R₆. In some instances, the R₃ structuresare different from the structure of R₆. In some instances, m is 0 and R₃and R₅ each have a structure according to:

and the structures for R₃ are different from the structure for R₅ or thesame as the structure for R₅.

When a polysiloxane according to General Formula I is to be employed inan electrolyte, a suitable average molecular weight for the polysiloxaneincludes, but is not limited to, an average molecular weight less thanor equal to 3000 g/mole.

The solvent can include or consist of one or more tetrasiloxanes.Tetrasiloxanes can have a reduced viscosity relative to similarlystructured tetrasiloxanes. A suitable tetrasiloxane has a backbone withtwo central silicons and two terminal silicons. One or more of thesilicons can be linked to a first substituent and/or to a secondsubstituent. The first substituent includes a poly(alkylene oxide)moiety and the second substituent includes a cyclic carbonate moiety.Suitable first substituents include side chains or cross links to othertetrasiloxanes. Further, each of the first substituents can be the sameor different. In one example of the tetrasiloxane, each of the firstsubstituents is a side chain. Suitable second substituents include sidechains. Further, each of the second substituents can be the same ordifferent. Each of the second substituents can be the same or different.In some instances, the terminal silicons in the backbone are not linkedto either a first substituent or a second substituent. Each of thecentral silicons can be linked to at least one first substituent or toat least one second substituent. In some instances, the tetrasiloxaneexcludes second substituents. One or more of the silicons in thebackbone of the tetrasiloxane can be linked to a cross-link to anothertetrasiloxane. The cross-link can include a poly(alkylene oxide) moiety.Examples of suitable tetrasiloxanes are disclosed in U.S. patentapplication Ser. No. 11/056,868, filed on Feb. 10, 2005, entitled“Electrochemical Device Having Electrolyte Including Tetrasiloxane,” andU.S. patent application Ser. No. 10/971,926, filed on Oct. 21, 2004,entitled “Electrochemical Device Having Electrolyte IncludingTetrasiloxane,” and U.S. Provisional Patent Application Ser. No.60/543,951, filed on Feb. 11, 2004, entitled “Siloxane,” each of whichis incorporated herein in its entirety.

An example of a suitable tetrasiloxane includes a backbone with a firstsilicon linked to a first side chain that includes a poly(alkyleneoxide) moiety. Additionally, a second silicon in the backbone is linkedto a second side chain that includes a poly(alkylene oxide) moiety or acyclic carbonate moiety. In some instances, the first silicon and thesecond silicon are each terminal silicons. In other instances, the firstsilicon and the second silicon are each central silicons.

As the number of substituents that include a poly(alkylene oxide) moietyand/or a cyclic carbonate moiety increases, the viscosity of anelectrolyte can increase undesirably and/or the ionic conductivity of anelectrolyte can decrease undesirably. As a result, in some instances,the tetrasiloxane includes no more than two poly(alkylene oxide)moieties or no more than one poly(alkylene oxide) moiety. Additionallyor alternately, the tetrasiloxane can include no more than two carbonatemoieties or no more than one carbonate moiety. For instance, a third oneof the silicons and a fourth one of the silicons can each be linked toentities that each exclude a poly(alkylene oxide) moiety and/or thateach exclude a cyclic carbonate moiety. For instance, the third siliconand the fourth silicon can each be linked to substituents such as sidechains that each exclude a poly(alkylene oxide) moiety and/or that eachexclude a cyclic carbonate moiety. In some instances, the entitieslinked to the backbone of the tetrasiloxane other than the first sidechain and the second side chain each exclude a poly(alkylene oxide)moiety and/or a cyclic carbonate moiety. For instance, the entitieslinked to the backbone of the tetrasiloxane other than the first sidechain and the second side chain can each be a substituent such as a sidechain and each of these substituents can exclude a poly(alkylene oxide)moiety and/or a cyclic carbonate moiety.

A silicon on the tetrasiloxane backbone can be linked directly to apoly(alkylene oxide) moiety or a spacer can be positioned between thepoly(alkylene oxide) moiety and the silicon. The spacer can be anorganic spacer. When the first silicon and the second silicon are eachcentral silicons linked directly to a side chain that includes apoly(alkylene oxide) moiety, the poly(alkylene oxide) moieties eachinclude an oxygen linked directly to the backbone. The poly(alkyleneoxide) moiety can be an oligo(alkylene oxide) moiety. In some instances,the poly(alkylene oxide) moiety is a poly(ethylene oxide) moiety.

When a silicon is linked to side chains that includes a cyclic carbonatemoiety, the side chain can include a spacer that links the carbonatemoiety to the silicon or an oxygen can link the cyclic carbonate moietyto the silicon. The spacer can be an organic spacer.

In instances where the first silicon and the second silicons are eachterminal silicons, the first and second silicons can each be linked to aside chain that includes a poly(alkylene oxide) moiety. Formula IIIprovides an example of a tetrasiloxane where the first silicon and thesecond silicon are each terminal silicons linked to a side chain thatincludes a polyethylene oxide moiety. Formula III:

wherein R₁ is an alkyl group; R₂ is an alkyl group; R₃ is an alkyl groupor an aryl group; R₄ is an alkyl group or an aryl group; R₅ is an alkylgroup or an aryl group; R₆ is an alkyl group or an aryl group; R₇ is nilor a spacer; R₈ is nil or a spacer; R₉ is a hydrogen, an alkyl group oran aryl group; R₁₀ is a hydrogen, an alkyl group or an aryl group; R₁₁is an alkyl group or an aryl group; and R₁₂ is an alkyl group or an arylgroup; x is 1 or greater and/or 12 or less and y is 1 or greater and/or12 or less. One or more of the alkyl and/or aryl groups can besubstituted, unsubstituted, halogenated, and/or fluorinated. The spacerscan be organic spacers and can include one or more —CH₂— groups. Othersuitable spacers can include an alkylene, alkylene oxide or a bivalentether group. These spacers can be substituted or unsubstituted. Theabove spacers can be completely or partially halogenated. For instance,the above spacers can be completely or partially fluorinated. In oneexample, R₇ and R₈ are each nil or are each a spacer. In one example, R₇and/or R₈ is represented by: —(CH₂)₃—. In one example: R₁; R₂; R₃; R₄;R₅; R₆; R₁₁; and R₁₂ are each methyl groups.

Examples of preferred tetrasiloxanes according to Formula III arerepresented by Formula III-A through Formula III-B. Formula III-Aillustrates an example of a tetrasiloxane having terminal siliconslinked to side chains that include an organic spacer linking apoly(alkylene oxide) moiety to a terminal silicon. Formula III-Billustrates an example of a tetrasiloxane having terminal silicons thatare each linked to an oxygen included in a poly(alkylene oxide) moiety.

Formula III-A:

wherein n is 1 to 12 and m is 1to 12.

Formula III-B:

wherein n is 1 to 12 and m is 1 to 12.

Another suitable tetrasiloxane has a backbone with one of two centralsilicons linked to a side chain that includes a poly(alkylene oxide)moiety and the other central silicon linked to a side chain thatincludes a poly(alkylene oxide) moiety or a carbonate moiety. When eachof the central silicons is linked to a side chain that includes apoly(alkylene oxide) moiety, the poly(alkylene oxide) moieties eachinclude an oxygen linked directly to a silicon in the backbone.

Another example of a suitable tetrasiloxane is represented by FormulaIV.

Formula IV:

wherein: R₂₀ is an alkyl group or an aryl group; R₂₁ is an alkyl groupor an aryl group; R₂₂ is represented by Formula IV-A; R₂₃ is representedby Formula IV-B or IV-C and each Z is an alkyl or an aryl group. The Zscan be the same or can be different.

Formula IV-A:

wherein R₂₄ is an organic spacer or nil; R₂₅ is hydrogen, alkyl or aryl;R₂₆ is alkyl or aryl and p is 1 or more and/or 12 or less. The organicspacer and can include one or more —CH₂— groups. Other suitable spacerscan include an alkylene, alkylene oxide or a bivalent ether group. Thesespacers can be substituted or unsubstituted. The above spacers can becompletely or partially halogenated. For instance, the above spacers canbe completely or partially fluorinated. In one example, R₂₄ isrepresented by: —(CH₂)₃—.

Formula IV-B:

wherein R₂₈ is hydrogen, alkyl or aryl; R₂₉ is alkyl or aryl; q is 1 ormore and/or 12 or less.

Formula IV-C:

wherein R₃₀ is an organic spacer and r is 1 or 2. Suitable organicspacers for Formula IV through N—C can include one or more —CH₂— groups.Other suitable spacers can include an alkylene, alkylene oxide or abivalent ether group. These spacers can be substituted or unsubstituted.The above spacers can be completely or partially halogenated. Forinstance, the above spacers can be completely or partially fluorinated.In one example, R₃₀ is a bivalent ether moiety represented by:—CH₂—O—(CH₂)₃— with the —(CH₂)₃— linked to a silicon on the backbone ofthe tetrasiloxane. In another example, R₃₀ is an alkylene oxide moietyrepresented by: —CH₂—O— with the oxygen linked to a silicon on thebackbone of the tetrasiloxane.

One or more of the alkyl and aryl groups specified in Formula IV throughFormula IV-C can be substituted, unsubstituted, halogenated, and/orfluorinated. When R₂₃ is according to Formula IV-B, R₂₄ can be nil orcan be a spacer. In one example, R₂₃ is according to Formula IV-C andR₃₀ is represented by: —CH₂—O—(CH₂)₃— where the single —CH₂— group ispositioned between the carbonate and the oxygen. In an example, the Zs,R₂₀, R₂₁, R₂₆, and R₂₉ are each a methyl group. In another example, R₂₂is represented by Formula IV-A and R₂₃ is represented by Formula IV-Band in another example R₂₃ is represented by Formula IV-A and R₂₃ isrepresented by Formula IV-C.

Examples of tetrasiloxanes according to Formula IV are represented byFormula IV-D through Formula IV-F. Formula IV-D represents atetrasiloxane where each of the central silicons is linked to a sidechain that includes a poly(ethylene oxide) moiety. The central siliconsare each linked directly to an oxygen included in a poly(ethylene oxide)moiety. Formula IV-E and Formula IV-F each represent an example of atetrasiloxane wherein a central silicon is linked to a side chain thatincludes a poly(alkylene oxide) moiety and another central silicon islinked to a side chain that includes a carbonate moiety. In FormulaIV-E, an organic spacer is positioned between the poly(alkylene oxide)moiety and the silicon. In Formula IV-F, a silicon is linked directly toan oxygen included in a poly(alkylene oxide) moiety.

Formula IV-D:

wherein n is 1 to 12.

Formula IV-E:

wherein n is 1 to 12.

Formula IV-F:

wherein n is 1 to 12.

The solvent can include or consist of one or more trisiloxanes.Trisiloxanes can have a reduced viscosity relative to similarlystructured, polysiloxanes and tetrasiloxanes. A suitable trisiloxane hasa backbone with three silicons. One or more of the silicons is linked toa first substituent and/or to a second substituent. The firstsubstituent includes a poly(alkylene oxide) moiety and the secondsubstituent includes a cyclic carbonate moiety. Suitable firstsubstituents include side chains or cross links to other trisiloxanes.When the trisiloxanes includes more than one first substituent, each ofthe first substituents can be the same or different. In one example ofthe polysiloxane, each of the first substituents is a side chain.Suitable second substituents include side chains. When the trisiloxanesincludes more than one second substituent, each of the secondsubstituents can be the same or different. In some instances, theterminal silicons in the backbone are not linked to either a firstsubstituent or a second substituent. The central silicons can be linkedto at least one first substituent or to at least one second substituent.In some instances, the trisiloxane excludes second substituents. One ormore of the silicons in the backbone of the trisiloxane can be linked toa cross-link to another trisiloxane. The cross-link can include apoly(alkylene oxide) moiety. Examples of suitable trisiloxanes aredisclosed in U.S. patent application Ser. No. 11/056,867, filed on Feb.10, 2005, entitled “Electrochemical Device Having Electrolyte IncludingTrisiloxane,” incorporated herein in its entirety, and U.S. patentapplication Ser. No. 10/971,913, filed on Oct. 21, 2004, entitled“Electrochemical Device Having Electrolyte Including Trisiloxane,”incorporated herein in its entirety, and U.S. Provisional PatentApplication Ser. No. 60/543,951, filed on Feb. 11, 2004, entitled“Siloxane,” and incorporated herein in its entirety; and U.S.Provisional Patent Application Ser. No. 60/542,017, filed on Feb. 4,2004, entitled “Nonaqueous Electrolyte Solvents for ElectrochemicalDevices,” and incorporated herein in its entirety; and U.S. ProvisionalPatent Application Ser. No. 60/543,898, filed on Feb. 11, 2004, entitled“Siloxane Based Electrolytes for Use in Electrochemical Devices,” andincorporated herein in its entirety.

A suitable trisiloxane includes a backbone with a first terminalsilicon, a central silicon and a second terminal silicon. The firstterminal silicons is linked to a first side chain that includes apoly(alkylene oxide) moiety or that includes a cyclic carbonate moiety.The second terminal silicon is linked to a second side chain thatincludes a poly(alkylene oxide) moiety or that includes a cycliccarbonate moiety. The first side chain and the second side chain caneach include a poly(alkylene oxide) moiety or can each include a cycliccarbonate moiety. Alternately, the first side can include apoly(alkylene oxide) moiety and the second side chain can include acyclic carbonate moiety. In one example, the second side chain includesa cyclic carbonate moiety and the first side chain includes an organicspacer linking a poly(alkylene oxide) moiety to the first terminalsilicon.

As the number of substituents that include a poly(alkylene oxide) moietyand/or a cyclic carbonate moiety increase, the viscosity of anelectrolyte can increase undesirably and/or the ionic conductivity of anelectrolyte can decrease undesirably. As a result, the trisiloxane caninclude no more than two poly(alkylene oxide) moieties or no more thanone poly(alkylene oxide) moiety. Additionally or alternately, thetrisiloxane can include no more than two carbonate moieties or no morethan one carbonate moiety. For instance, each of the entities linked tothe central silicon can exclude a poly(alkylene oxide) moiety and/or acyclic carbonate moiety. Additionally or alternately, the entitieslinked to the first terminal silicon other than the first side chain andthe entities linked to the second terminal silicon other than the secondside chain can each exclude a poly(alkylene oxide) moiety and/or acyclic carbonate moiety. In one example, each of the entities linked tothe silicons in the backbone of the trisiloxane other than the firstside chain and other than the second side chain exclude both apoly(alkylene oxide) moiety and a cyclic carbonate moiety. Examples ofentities that may be linked to the silicons include, but are not limitedto, substituents such as side chains, cross-links and halogens.

Formula V provides an example of the trisiloxane. Formula V:

wherein R₁ is an alkyl group; R₂ is an alkyl group; R₃ is an alkyl groupor an aryl group; R₄ is an alkyl group or an aryl group; R₅ is an alkylgroup or an aryl group; R₆ is an alkyl group or an aryl group; R₇ isrepresented by Formula V-A or Formula V-B; R₈ is represented by FormulaV-C or Formula V-D.

Formula V-A:

wherein R₉ is nil or a spacer; R₁₀ is hydrogen; alkyl or aryl; R₁₁ isalkyl or aryl; and n is 1 to 12. The spacer can be an organic spacer andcan include one or more —CH₂— groups. Other suitable spacers can includean alkylene, alkylene oxide or a bivalent ether group. These spacers canbe substituted or unsubstituted. The above spacers can be completely orpartially halogenated. For instance, the above spacers can be completelyor partially fluorinated. In one example, R₉ is represented by:—(CH₂)₃—.

Formula V-B:

wherein R₁₂ is an organic spacer and p is 1 to 2. The spacer can be anorganic spacer and can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide or a bivalent ethergroup. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₁₂ is a bivalent ether moiety represented by: —CH₂—O—(CH₂)₃—with the —(CH₂)₃— linked to a silicon on the backbone of thetrisiloxane. In another example, R₁₂ is a alkylene oxide moietyrepresented by: —CH₂—O— with the oxygen linked to a silicon on thebackbone of the trisiloxane.

Formula V-C:

wherein R₁₃ is nil or a spacer; R₁₄ is hydrogen; alkyl or aryl; R₁₅ isalkyl or aryl; and q is 1 to 12. The spacer can be an organic spacer andcan include one or more —CH₂— groups. Other suitable spacers can includean alkylene, alkylene oxide or a bivalent ether group. These spacers canbe substituted or unsubstituted. The above spacers can be completely orpartially halogenated. For instance, the above spacers can be completelyor partially fluorinated. In one example, R₁₃ is represented by:—(CH₂)₃—.

Formula V-D:

wherein R₁₆ is an organic spacer and p is 1 to 2. The spacer can be anorganic spacer and can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide or a bivalent ethergroup. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₁₆ is a bivalent ether moiety represented by: —CH₂—O—(CH₂)₃—with the —(CH₂)₃— linked to a silicon on the backbone of thetrisiloxane. In another example, R₁₆ is a alkylene oxide moietyrepresented by: —CH₂—O— with the oxygen linked to a silicon on thebackbone of the trisiloxane.

One or more of the alkyl and aryl groups specified in Formula V throughFormula V-D can be substituted, unsubstituted, halogenated, and/orfluorinated. In one example of a trisiloxane according to Formula V, R₇is represented by Formula V-A with R₉ as an organic spacer and R₈ isrepresented by Formula V-C with R₁₃ as an organic spacer. In anotherexample of a trisiloxane according to Formula V, R₇ is represented byFormula V-A with R₉ as nil and R₈ is represented by Formula V-C with R₁₃as nil. In another example of a trisiloxane according to Formula V, R₇is represented by Formula V-B and R₈ is represented by Formula V-D. Inanother example of a trisiloxane according to Formula V, R₇ isrepresented by Formula V-A with R₉ as an organic spacer and R₈ isrepresented by Formula V-D. In another example of a trisiloxaneaccording to Formula V, R₇ is represented by Formula V-A with R₉ as anorganic spacer and R₈ is represented by Formula V-D. In some instances,R₁, R₂, R₃, R₄, R₅, and R₆ is each a methyl group.

Formula V-E through Formula V-H are examples of trisiloxanes accordingto Formula V. Formula V-E and Formula V-F each illustrate a trisiloxanewhere each of the terminal silicons are linked to a side chain thatincludes a poly(ethylene oxide) moiety. Formula V-E illustrates anorganic spacer positioned between each poly(ethylene oxide) moiety andthe terminal silicon. Formula V-F illustrates each of the terminalsilicons linked directly to a poly(ethylene oxide) moiety.

Formula V-E:

wherein n is 1 to 12 and m is 1to 12.

Formula V-F:

wherein n is 1 to 12 and m is 1to 12.

Formula V-G and Formula V-H each illustrate a trisiloxane with aterminal silicon linked to a side chain that includes a cyclic carbonatemoiety. Formula V-G illustrates one of the terminal silicon linked to aside chain that includes a cyclic carbonate moiety and one of theterminal silicons linked to a side chain that includes a poly(ethyleneoxide) moiety. Formula V-H illustrates each of the terminal siliconslinked to a side chain that includes a cyclic carbonate moiety.

Formula V-G:

wherein m is 1 to 12.

Formula V-H:

Another suitable trisiloxane includes a backbone with a first terminalsilicon, a central silicon and a second terminal silicon. The centralsilicon is linked to a central substituent. The central substituent canbe a side chain that includes a cyclic carbonate moiety, or thatincludes a poly(alkylene oxide) moiety linked directly to the centralsilicon. Alternately, the central substituent can be a cross-link thatcross links the trisiloxane to a second siloxane and that includes apoly(alkylene oxide) moiety.

In some instances, the trisiloxane includes not more than twopoly(alkylene oxide) moieties or not more than one poly(alkylene oxide)moiety. Additionally or alternately, the trisiloxane can include notmore than two carbonate moieties or not more than one carbonate moiety.The entities linked to the first terminal silicon and the entitieslinked to the second terminal silicon can each exclude a poly(alkyleneoxide) moiety and/or each exclude a cyclic carbonate moiety.Additionally or alternately, the entities linked to the central silicon,other than the central substituent, can exclude a poly(alkylene oxide)moiety and/or exclude a cyclic carbonate moiety. In one example, each ofthe entities linked to the silicons in the backbone of the trisiloxane,other than the central substituent, exclude both a poly(alkylene oxide)moiety and a cyclic carbonate moiety. Examples of entities that may belinked to the silicons include, but are not limited to, substituentssuch as side chains, halogens and cross-links.

An example of the trisiloxane is represented by the following FormulaVI:

wherein R₁₉ is an alkyl group or an aryl group; R₂₀ is represented byFormula VI-A, Formula VI-B or Formula VI-C; and the Zs are each an alkylor an aryl group and can be the same or different.

Formula VI-A:

wherein R₂₁ is an organic spacer and p is 1 to 2. Suitable organicspacers can include one or more —CH₂— groups. Other suitable spacers caninclude an alkylene, alkylene oxide or a bivalent ether group. Thesespacers can be substituted or unsubstituted. The above spacers can becompletely or partially halogenated. For instance, the above spacers canbe completely or partially fluorinated. In one example, R₂₁ is abivalent ether moiety represented by: —CH₂—O—(CH₂)₃— with the —(CH₂)₃—linked to a silicon on the backbone of the trisiloxane. In anotherexample, R₂₁ is a alkylene oxide moiety represented by: —CH₂—O— with theoxygen linked to a silicon on the backbone of the trisiloxane.

Formula VI-B:

wherein R₂₃ is hydrogen; alkyl or aryl; R₂₄ is alkyl or aryl; and r is 1to 12. The spacer can be an organic spacer and can include one or more—CH₂— groups. Other suitable spacers can include an alkylene, alkyleneoxide or a bivalent ether group. These spacers can be substituted orunsubstituted. The above spacers can be completely or partiallyhalogenated. For instance, the above spacers can be completely orpartially fluorinated. In one example, R₂₂ is represented by: —(CH₂)₃—.

Formula VI-C:

where R₂₅ is nil or a spacer; R₂₆ is nil or a spacer; R₂₇ is hydrogen,alkyl or aryl; second siloxane represents another siloxane and n is 1 to12. When R₂₅ and/or R₂₆ is a spacer, the spacer can be an organic spacerand can include one or more —CH₂— groups. Other suitable spacers caninclude an alkylene, alkylene oxide or a bivalent ether group. Thesespacers can be substituted or unsubstituted. The above spacers can becompletely or partially halogenated. For instance, the above spacers canbe completely or partially fluorinated. When R₂₆ is a spacer, R₂₆ can belinked to a silicon in the backbone of the second siloxane. When R₂₆ isnil, the poly(ethylene oxide) moiety can be linked to a silicon in thebackbone of the second siloxane. The second siloxane can representanother trisiloxane. When the second siloxane is a trisiloxane, R₂₆ orthe poly(ethylene oxide) moiety can be linked to a central silicon inthe backbone of the second trisiloxane.

One or more of the alkyl and aryl groups specified in Formula VI throughFormula VI-C can be substituted, unsubstituted, halogenated, and/orfluorinated. In one example of a trisiloxane according to Formula VI,R₂₀ is represented by Formula VI-A. In another example of thetrisiloxane, R₂₀ is represented by Formula VI-B. In another example, R₂₀is represented by Formula VI-C, R₂₅ is nil, R₂₆ is nil and thepoly(ethylene oxide) moiety is linked to a silicon in the backbone ofthe second siloxane. In another example, R₂₀ is represented by FormulaVI-C, R₂₅ is a spacer, R₂₆ is a spacer linked to a silicon in thebackbone of the second siloxane. In another example, R₂₅ is a spacerwith the same structure as R₂₆. In another example of a trisiloxaneaccording to Formula VI, R₁₉ and each of the Z represent methyl groups.

Formula VI-D through Formula VI-F are examples of trisiloxanes accordingto Formula VI. Formula VI-D illustrates a trisiloxane where the centralsilicon is linked to a side chain that includes a poly(ethylene oxide)moiety linked directly to the central silicon.

Formula VI-D:

wherein n is 1 to 12.

Formula VI-E and Formula VI-F illustrate trisiloxanes having a centralsilicon linked to a cross link that includes a poly(ethylene oxide)moiety and that cross-links the trisiloxane to a second trisiloxane.Formula VI-E illustrates the cross link including a spacer positionedbetween the poly(ethylene oxide) moiety and each of the trisiloxanes.Formula VI-F illustrates a silicon in the backbone of each trisiloxanelinked directly to a poly(ethylene oxide) moiety. Formula VI-E:

wherein n is 1 to 12.Formula VI-F:

wherein n is 1 to 12.

The solvent can include or consist of one or more disiloxanes.Disiloxanes can have a reduced viscosity relative to similarlystructured, polysiloxanes, tetrasiloxanes and trisiloxanes. An exampleof a suitable disiloxane includes a backbone with a first silicon and asecond silicon. The first silicon is linked to one or more firstsubstituents that each include a poly(alkylene oxide) moiety or a cycliccarbonate moiety. The first substituent can be selected from a groupconsisting of a first side-chain that includes a poly(alkylene oxide)moiety, a first side-chain that includes a cyclic carbonate moiety or across link that includes a poly(alkylene oxide) moiety and that crosslinks the disiloxane to a second siloxane wherein side chains areexclusive of cross links. As the number of substituents that include apoly(alkylene oxide) moiety and/or a cyclic carbonate moiety increase,the viscosity of an electrolyte can increase undesirably and/or theionic conductivity of an electrolyte can decrease undesirably. As aresult, embodiments of the disiloxane include no more than onepoly(alkylene oxide) moiety and/or no more than one cyclic carbonatemoiety. For instance, the entities linked to the first silicon and thesecond silicon, other than the first substituent, can each exclude apoly(alkylene oxide) moiety and/or a cyclic carbonate moiety. In someinstances, the disiloxane excludes a poly(alkylene oxide) moieties orexcludes cyclic carbonate moieties.

The second silicon can be linked to a second substituent selected from agroup consisting of a second side-chain that includes a poly(alkyleneoxide) moiety, a second side-chain that includes a cyclic carbonatemoiety, an aryl group or an alkyl group. In some instances, the secondsubstituent is selected from a group consisting of a second side-chainthat includes a poly(alkylene oxide) moiety and a second side-chain thatincludes a cyclic carbonate moiety. As noted above, the viscosity of anelectrolyte can increase undesirably and/or the ionic conductivity of anelectrolyte can decrease undesirably as the number of substituents thatinclude a poly(alkylene oxide) moiety and/or a cyclic carbonate moietyincreases. As a result, the disiloxanes can include no more than twopoly(alkylene oxide) moiety and/or no more than two cyclic carbonatemoiety. For instance, the entities linked to the first silicon and thesecond silicon, in addition to the first substituent and the secondsubstituent, can each exclude a poly(alkylene oxide) moiety and/or acyclic carbonate moiety.

Examples of suitable disiloxanes are disclosed in U.S. patentapplication Ser. No. 11/056,866, filed on Feb. 10, 2005, entitled“Electrochemical Device Having Electrolyte Including Disiloxane,” andU.S. patent application Ser. No. 10/971,507, filed on Oct. 21, 2004,entitled “Electrochemical Device Having Electrolyte IncludingDisiloxane,” and U.S. Provisional Patent Application Ser. No.60/543,951, filed on Feb. 11, 2004, entitled “Siloxane,” and U.S.Provisional Patent Application Ser. No. 60/542,017, filed on Feb. 4,2004, entitled “Nonaqueous Electrolyte Solvents for ElectrochemicalDevices,” and U.S. Provisional Patent Application Ser. No. 60/543,898,filed on Feb. 11, 2004, entitled “Siloxane Based Electrolytes for Use inElectrochemical Devices;” each of which is incorporated herein in itsentirety.

Formula VII provides an example of a suitable disiloxane. Formula VII:

wherein R₁ is an alkyl group or an aryl group; R₂ is an alkyl group oran aryl group; R₃ is an alkyl group or an aryl group; R₄ is an alkylgroup or an aryl group; R₅ is represented by Formula VII-A, FormulaVII-B or Formula VII-C; R₆ is an alkyl group, an aryl group, representedby Formula VII-D, or represented by Formula VII-E.

Formula VVI-A:

wherein R₉ is nil or a spacer; R₁₀ is hydrogen; alkyl or aryl; R₁₁ isalkyl or aryl; and n is 1 to 12. The spacer can be an organic spacer andcan include one or more —CH₂— groups. Other suitable spacers can includean alkylene, alkylene oxide or a bivalent ether group. These spacers canbe substituted or unsubstituted. The above spacers can be completely orpartially halogenated. For instance, the above spacers can be completelyor partially fluorinated. In one example, R₉ is represented by:—(CH₂)₃—.

Formula VII-B:

wherein R₁₂ is an organic spacer and p is 1 to 2. The spacer can be anorganic spacer and can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide or a bivalent ethergroup. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₁₂ is a bivalent ether moiety represented by: —CH₂—O—(CH₂)₃—with the —(CH₂)₃— linked to a silicon on the backbone of the disiloxane.In another example, R₁₂ is a alkylene oxide moiety represented by:—CH₂—O— with the oxygen linked to a silicon on the backbone of thedisiloxane.

Formula VII-C:

where R₁₄ is nil or a spacer; R₁₅ is nil or a spacer; R₁₆ is hydrogen,alkyl or aryl; second siloxane represents another siloxane and n is 1 to12. The spacers can be organic spacers and can include one or more —CH₂—groups. Other suitable spacers can include an alkylene, alkylene oxideor a bivalent ether group. These spacers can be the same or differentand can be substituted or unsubstituted. The above spacers can becompletely or partially halogenated. For instance, the above spacers canbe completely or partially fluorinated. In one example, R₁₄ and R₁₅ areeach represented by: —(CH₂)₃—.

Formula VII-D:

wherein R₁₇ is nil or a spacer; R₁₈ is hydrogen; alkyl or aryl; R₁₉ isalkyl or aryl; and q is 1 to 12. The spacer can be an organic spacer andcan include one or more —CH₂— groups. Other suitable spacers can includean alkylene, alkylene oxide or a bivalent ether group. These spacers canbe substituted or unsubstituted. The above spacers can be completely orpartially halogenated. For instance, the above spacers can be completelyor partially fluorinated. In one example, R₁₇ is represented by:—CH₂—O—(CH₂)₃— with the —(CH₂)₃— linked to a silicon on the backbone ofthe disiloxane.

Formula VII-E:

wherein R₂₀ is an organic spacer and p is 1 to 2. The spacer can be anorganic spacer and can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide or a bivalent ethergroup. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₂₀ is a bivalent ether moiety represented by: —CH₂—O—(CH₂)₃—with the —(CH₂)₃— linked to a silicon on the backbone of the disiloxane.In another example, R₂₀ is a alkylene oxide moiety represented by:—CH₂—O— with the oxygen linked to a silicon on the backbone of thedisiloxane.

In the disiloxanes illustrated in Formula VII: R₅ can represent FormulaVII-A or Formula VII-B; or R₅ can represent Formula VII-A or FormulaVII-C; or R₅ can represent Formula VII-B or Formula VII-C. Additionallyor alternately: R₆ can represent an alkyl group or an aryl group orFormula VII-D; R₆ can represent an alkyl group or an aryl group orFormula VII-E. In some instances, R₁, R₂, R₃ and R₄ are each an alkylgroup. For instance, R₁, R₂, R₃ and R₄ can each be a methyl group.

In one example of the disiloxane, the first substituent is a side chainthat includes a poly(alkylene oxide) moiety. The poly(alkylene oxide)moiety can include an oxygen linked directly to the first silicon. Forinstance, the disiloxanes can be represented by Formula VII with R₅represented by Formula VII-A and R₉ as nil. Alternately, a spacer canlink the poly(alkylene oxide) moiety to the first silicon. For instance,the disiloxanes can be represented by Formula VII with R₅ represented byFormula VII-A and R₉ as a divalent organic moiety.

When the first substituent is a side chain that includes a poly(alkyleneoxide) moiety, each of the entities linked to the second silicon can bealkyl groups and/or aryl groups. For instance, the second substituentcan be an alkyl group or an aryl group. The disiloxanes can berepresented by Formula VII with R₅ represented by Formula VII-A and R₆as an alkyl group or an aryl group. Formula VII-F provides an example ofthe disiloxane. Formula VII-F:

where R₂₁ is an alkyl group or an aryl group; R₂₂ is an alkyl group oran aryl group; R₂₃ is nil or a spacer; R₂₄ is a hydrogen atom or analkyl group; R₂₅ is an alkyl group; Z is an alkyl or an aryl group andthe Zs can be the same or different and x is from 1 to 30. The spacercan be an organic spacer and can include one or more —CH₂— groups. Othersuitable spacers can include an alkylene, alkylene oxide or a bivalentether group. These spacers can be substituted or unsubstituted. Theabove spacers can be completely or partially halogenated. For instance,the above spacers can be completely or partially fluorinated. In oneexample, R₂₃ has a structure according to: —(CH₂)₃—. In another example,the Zs, R₂₁, R₂₂ and R₂₅ are each a methyl group. In a preferredexample, the Zs, R₂₁, R₂₂ and R₂₅ are each a methyl group, R₂₃ has astructure according to: —(CH₂)₃— and R₂₄ is a hydrogen. In a morepreferred example, the Zs, R₂₁, R₂₂ and R₂₅ are each a methyl group, R₂₃has a structure according to: —(CH₂)₃—; R₂₄ is a hydrogen; and x is 3. Apreferred example of the disiloxane is provided in the following FormulaVII-G:

wherein n is 1 to 12. A particularly preferred disiloxane is representedby Formula VII-G with n=3.

When the first substituent is a side chain that includes a poly(alkyleneoxide) moiety, the second substituent can be a side chain that includesa poly(alkylene oxide) moiety. For instance, the disiloxane can berepresented by Formula VII with R₅ represented by Formula VII-A and R₆represented by Formula VII-D. An example of the disiloxanes is providedin the following Formula VII-H:

wherein R₂₆ is an alkyl group or an aryl group; R₂₇ is an alkyl group oran aryl group; R₂₈ is nil or a spacer; R₂₉ is a hydrogen atom or analkyl group; R₃₀ is an alkyl group; R₃₁ is an alkyl group or an arylgroup; R₃₂ is an alkyl group or an aryl group; R₃₃ is nil or a spacer;R₃₄ is a hydrogen atom or an alkyl group; R₃₅ is an alkyl group; x isfrom 1 to 30 and y is from 1 to 30. R₂₈ and R₃₃ can be the same ordifferent. Each spacer can be an organic spacer and can include one ormore —CH₂— groups. Other suitable spacers can include an alkylene,alkylene oxide or bivalent ether. These spacers can be substituted orunsubstituted. The above spacers can be completely or partiallyhalogenated. For instance, the above spacers can be completely orpartially fluorinated. In one example, R₂₈ and R₃₃ each has a structureaccording to: —(CH₂)₃—. In another example, R₂₆, R₂₇, R₃₁, and R₃₂ areeach an alkyl group. In another example, R₂₆, R₂₇, R₃₀, R₃₁, R₃₂, andR₃₅ are each a methyl group. In another example, R₃₀ and R₃₅ have thesame structure, R₂₉ and R₃₄ have the same structure, R₂₈ and R₃₃ havethe same structure and R₂₆, R₂₇, R₃₁, and R₃₂ have the same structure. Apreferred example of the disiloxane is presented in Formula VII-J:

wherein n is 1 to 12 and m is 1 to 12. A particularly preferreddisiloxane is represented by Formula VII-J with n=3 and m=3.

When the first substituent is a side chain that includes a poly(alkyleneoxide) moiety, the second substituent can be a side chain that includesa cyclic carbonate moiety. For instance, the disiloxane can berepresented by Formula VII with R₅ represented by Formula VII-A and R₆represented by Formula VII-E.

In another example of the disiloxane, the first substituent cross linksthe disiloxane to a second siloxane and includes a poly(alkylene oxide)moiety. The poly(alkylene oxide) moiety can include an oxygen linkeddirectly to the first silicon. For instance, the disiloxane can berepresented by Formula VII with R₅ represented by Formula VII-C and R₁₄as nil. In some instances, the poly(alkylene oxide) moiety also includesa second oxygen liked directly to the backbone of the second siloxane.For instance, the disiloxane can be represented by Formula VII with R₅represented by Formula VII-C, R₁₄ as nil, and R₁₅ as nil. Alternately, aspacer can link the poly(alkylene oxide) moiety to the first silicon.For instance, the disiloxanes can be represented by Formula VII with R₅represented by Formula VII-A and R₁₄ as a divalent organic moiety. Insome instances, the poly(alkylene oxide) moiety also includes a secondspacer linking the poly(alkylene oxide) moiety to the backbone of thesecond siloxane. For instance, the disiloxane can be represented byFormula VII with R₅ represented by Formula VII-C, R₁₄ as a divalentorganic moiety, and R₁₅ as a divalent organic moiety.

When the first substituent cross links the disiloxane to a secondsiloxane and includes a poly(alkylene oxide) moiety, each of theentities linked to the second silicon can be an aryl group or an alkylgroup. For instance, the second substituent can be an alkyl group or anaryl group. The disiloxanes can be represented by Formula VII with R₅represented by Formula VII-C and R₆ as an alkyl group or an aryl group.Formula VII-K provides an example of the disiloxane where thepoly(alkylene oxide) moiety includes an oxygen linked directly to thefirst silicon. Formula VII-K:

wherein n is 1 to 12. Formula VII-L provides an example of thedisiloxane where an organic spacer is positioned between thepoly(alkylene oxide) moiety and the first silicon. Formula VII-L:

wherein n is 1 to 12.

When the first substituent cross links the disiloxane to a secondsiloxane and includes a poly(alkylene oxide) moiety, the secondsubstituent can be a side chain that includes a poly(alkylene oxide)moiety. For instance, the disiloxanes can be represented by Formula VIIwith R₅ represented by Formula VII-C and R₆ represented by FormulaVII-D.

When the first substituent cross links the disiloxane to a secondsiloxane and includes a poly(alkylene oxide) moiety, the secondsubstituent can be a side chain that includes a cyclic carbonate moiety.For instance, the disiloxanes can be represented by Formula VII with R₅represented by Formula VII-C and R₆ represented by Formula VII-E.

In another example of the disiloxane, the first substituent is a sidechain that includes a cyclic carbonate moiety. For instance, thedisiloxane can be represented by Formula VII with R₅ represented byFormula VII-B.

When the first substituent is a side chain that includes a cycliccarbonate moiety, each of the entities linked to the second silicon canbe an aryl group or an alkyl group. For instance, the second substituentcan be an alkyl group or an aryl group. The disiloxane can berepresented by Formula VII with R₅ represented by Formula VII-B and withR₆ as an alkyl group or an aryl group. A preferred example of thedisiloxane is presented by the following Formula VII-M:

When the first substituent is a side chain that includes a cycliccarbonate moiety, the second substituent can be a side chain thatincludes a cyclic carbonate moiety. For instance, the disiloxane can berepresented by Formula VII with R₅ represented by Formula VII-B and R₆represented by Formula VII-E. The structure of the first substituent canbe the same as the structure of the second substituent or can bedifferent from the structure of the second substituent. A preferredexample of the disiloxane is presented by the following Formula VII-N:

The electrolyte can include a single disiloxane and none or more othersiloxanes. Alternately, the electrolyte can include two or moredisiloxanes and none or more other siloxanes. Examples of other suitablesiloxanes include, but are not limited to, the trisiloxanes,tetrasiloxanes, pentasiloxanes, oligosiloxanes or polysiloxanesdisclosed above. In some instances, at least one of the two or moredisiloxanes is chosen from those represented by Formula VII throughFormula VII-N. Alternately, each of the disiloxanes can be chosen fromthose represented by Formula VII through Formula VII-N.

The solvent can include or consist of one or more silanes. An example ofthe silane includes a silicon linked to one or more first substituentsthat each include a poly(alkylene oxide) moiety or a cyclic carbonatemoiety. When a first substituent includes a poly(alkylene oxide) moiety,the poly(alkylene oxide) moiety can include an oxygen linked directly tothe silicon. Alternately, the first substituent can include a spacerpositioned between the poly(alkylene oxide) moiety and the silicon.Suitable spacers include, but are not limited to, organic spacers. Insome instances, the poly(alkylene oxide) moiety is a poly(ethyleneoxide) moiety. In some instances, the poly(alkylene oxide) moiety is anoligo(alkylene oxide) moiety having from 1 to 15 alkylene oxide units.Examples of suitable silanes are disclosed in U.S. patent applicationSer. No. 11/056,869, filed on Feb. 10, 2005, and entitled “ElectrolyteIncluding Silane for Use in Electrochemical Devices;” and U.S. patentapplication Ser. No. 10/977,313, filed on Oct. 28, 2004, entitled“Electrolyte Including Silane for Use in Electrochemical Devices;” andin U.S. Provisional Patent Application Ser. No. 60/601,452, filed onAug. 13, 2004, entitled “Electrolyte Including Silane for Use inElectrochemical Devices” each of which is incorporated herein in itsentirety.

The silane can include only one of the first substituents linked to asilicon or a plurality of the first substituents linked to the silicon.When the silane includes a plurality of the first substituents, thesilane can include two of the first substituents, three of the firstsubstituents or four of the first substituents. When the silane includesfewer than four first substituents, the additional substituent(s) linkedto the silicon are second substituents that each exclude a poly(alkyleneoxide) moiety and a cyclic carbonate moiety. Suitable secondsubstituents include, but are not limited to, alkyl groups, aryl groupsand halogens. When the silane includes a plurality of firstsubstituents, the first substituents can each be the same or can bedifferent. In one example, the silane includes a plurality of the firstsubstituents and each of the first substituents is different.Alternately, the silane includes a plurality of the first substituentsand a portion of the first substituents is different from anotherportion of the first substituents.

Examples of the first substituents include: a side-chain that includes apoly(alkylene oxide) moiety; a side-chain that includes a cycliccarbonate moiety; and a cross link that includes a poly(alkylene oxide)moiety and that cross-links the silane to a second silane where a crosslink is exclusive of a side chain. Accordingly, the silane can includeone or more side-chains that each include a poly(alkylene oxide) moietyand/or one or more side-chains that each include a cyclic carbonatemoiety and/or one or more cross links that each include a poly(alkyleneoxide) moiety and that each cross-link the silane to a second silane.

In one example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety and linkedto one or more second substituents. In another example, the silaneincludes a silicon linked to one or more side-chains that each include acyclic carbonate moiety and linked to one or more second substituents.In another example, the silane includes a silicon linked to one or morecross links that each include a poly(alkylene oxide) moiety and linkedto one or more second substituents.

In an example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety; to one ormore side-chains that each include a cyclic carbonate moiety; and to oneor more second substituents. In another example, the silane includes asilicon linked to one or more side-chains that each include a cycliccarbonate moiety; to one or more cross links that each include apoly(alkylene oxide) moiety; and to one or more second substituents. Inanother example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety; to one ormore cross links that each include a poly(alkylene oxide) moiety; and toone or more second substituents.

In one example, the silane includes a silicon linked to four side-chainsthat each include a poly(alkylene oxide) moiety. Accordingly, the silanecan exclude cyclic carbonate moieties. In another example, the silaneincludes a silicon linked to four side-chains that each include a cycliccarbonate moiety. Accordingly, the silane can exclude poly(alkyleneoxide) moieties. In another example, the silane includes a siliconlinked to four cross links that each include a poly(alkylene oxide)moiety.

An example of the silane includes a silicon linked to one or more firstsubstituents that each include a poly(alkylene oxide) moiety or a cycliccarbonate moiety. When a first substituent includes a poly(alkyleneoxide) moiety, the poly(alkylene oxide) moiety can include an oxygenlinked directly to the silicon. Alternately, the first substituent caninclude a spacer positioned between the poly(alkylene oxide) moiety andthe silicon. Suitable spacers include, but are not limited to, organicspacers. In some instances, the poly(alkylene oxide) moiety is apoly(ethylene oxide) moiety. In some instances, the poly(alkylene oxide)moiety is an oligo(alkylene oxide) moiety having from 1 to 15 alkyleneoxide units.

The silane can include only one of the first substituents linked to asilicon or a plurality of the first substituents linked to the silicon.When the silane includes a plurality of the first substituents, thesilane can include two of the first substituents, three of the firstsubstituents or four of the first substituents. When the silane includesfewer than four first substituents, the additional substituent(s) linkedto the silicon are second substituents that each exclude a poly(alkyleneoxide) moiety and a cyclic carbonate moiety. Suitable secondsubstituents include, but are not limited to, alkyl groups, aryl groupsand halogens. When the silane includes a plurality of firstsubstituents, the first substituents can each be the same or can bedifferent. In one example, the silane includes a plurality of the firstsubstituents and each of the first substituents is different.Alternately, the silane includes a plurality of the first substituentsand a portion of the first substituents is different from anotherportion of the first substituents.

Examples of the first substituents include: a side-chain that includes apoly(alkylene oxide) moiety; a side-chain that includes a cycliccarbonate moiety; and a cross link that includes a poly(alkylene oxide)moiety and that cross-links the silane to a second silane where a crosslink is exclusive of a side chain. Accordingly, the silane can includeone or more side-chains that each include a poly(alkylene oxide) moietyand/or one or more side-chains that each include a cyclic carbonatemoiety and/or one or more cross links that each include a poly(alkyleneoxide) moiety and that each cross-link the silane to a second silane.

In one example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety and linkedto one or more second substituents. In another example, the silaneincludes a silicon linked to one or more side-chains that each include acyclic carbonate moiety and linked to one or more second substituents.In another example, the silane includes a silicon linked to one or morecross links that each include a poly(alkylene oxide) moiety and linkedto one or more second substituents.

In an example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety; to one ormore side-chains that each include a cyclic carbonate moiety; and to oneor more second substituents. In another example, the silane includes asilicon linked to one or more side-chains that each include a cycliccarbonate moiety; to one or more cross links that each include apoly(alkylene oxide) moiety; and to one or more second substituents. Inanother example, the silane includes a silicon linked to one or moreside-chains that each include a poly(alkylene oxide) moiety; to one ormore cross links that each include a poly(alkylene oxide) moiety; and toone or more second substituents.

In one example, the silane includes a silicon linked to four side-chainsthat each include a poly(alkylene oxide) moiety. Accordingly, the silanecan exclude cyclic carbonate moieties. In another example, the silaneincludes a silicon linked to four side-chains that each include a cycliccarbonate moiety. Accordingly, the silane can exclude poly(alkyleneoxide) moieties. In another example, the silane includes a siliconlinked to four cross links that each include a poly(alkylene oxide)moiety.

A suitable silane can be represented by the following Formula VIII:SiR_(4-x-y)R′_(x)R″_(y); wherein R is a second substituent and an alkylgroup, an aryl group or a halogen, R′_(x) is a first substituent thatincludes a poly(alkylene oxide) moiety and can be represented by FormulaVIII-A or Formula VIII-C, R″_(y) is a first substituent that includes acyclic carbonate moiety and can be represented by Formula VIII-B, xindicates the number of R′ substituents included in the silane and is 0to 4, y indicates the number of R″ substituents included in the silaneis 0 to 4,4-x−y indicates the number of R substituents, and x+y is atleast 1.

Formula VIII-A:

wherein R₉ is nil or an organic spacer; R₁₀ is hydrogen; alkyl or aryl;R₁₁ is alkyl or aryl; and n is 1 to 15. The spacer can be an organicspacer and can include one or more —CH₂— groups. Other suitable spacerscan include an alkylene, alkylene oxide or a bivalent ether group. Thesespacers can be substituted or unsubstituted. In one example, R₉ isrepresented by: —(CH₂)₃—.

Formula VIII-B:

wherein R₁₂ is an organic spacer and p is 1 to 2. The spacer can be anorganic spacer and can include one or more —CH₂— groups. Other suitablespacers can include an alkylene, alkylene oxide or a bivalent ethergroup. These spacers can be substituted or unsubstituted. The abovespacers can be completely or partially halogenated. For instance, theabove spacers can be completely or partially fluorinated. In oneexample, R₁₂ is a bivalent ether moiety represented by: —CH₂—O—(CH₂)₃—with the —(CH₂)₃— linked to a silicon on the backbone of the silane. Inanother example, R₁₂ is an alkylene oxide moiety represented by: —CH₂—O—with the oxygen linked to a silicon on the backbone of the silane.

Formula VIII-C:

where R₁₄ is nil or a spacer; R₁₅ is nil or a spacer; R₁₆ is hydrogen,alkyl or aryl; second silane represents another silane and n is 1 to 15.The spacers can be organic spacers and can include one or more —CH₂—groups. Other suitable spacers can include an alkylene, alkylene oxideor a bivalent ether group. These spacers can be the same or differentand can be substituted or unsubstituted. In one example, R₁₄ and R₁₅ areeach represented by: —(CH₂)₃—. The second silane can be represented by:—SiR_(3-p-q)R′_(p)R″_(q), wherein R are each an alkyl group or an arylgroup, R′ is a substituent that includes a poly(alkylene oxide) moietyand can be represented by Formula VIII-A or Formula VIII-C, R″ is asubstituent that includes a cyclic carbonate moiety and can berepresented by Formula VIII-B, p is the number of R′ substituentsincluded on the second silane and is 0 to 3, q is the number of R″substituents included on the second silane, 3-p−q is the number of Rsubstituents, and is 0 to 3. In one example, p is 0 and q is 0. Inanother example, p+q is greater than or equal to 1. In yet anotherexample, p is greater than or equal to 1. In still another example, q isgreater than or equal to 1. In another example, R′ is represented byFormula VIII-A and R″ is represented by Formula VIII-B, p is 0 to 3 andq is 0 to 3.

One or more of the alkyl and aryl groups specified in Formula VIIIthrough Formula VIII-C can be substituted, unsubstituted, halogenated,and/or fluorinated. When the silane includes more than one substituentrepresented by Formula VIII-A, the entities can be the same ordifferent. When the silane includes more than one substituentrepresented by Formula VIII-B, the entities can be the same ordifferent. When the silane includes more than one substituentrepresented by Formula VIII-C, the entities can be the same ordifferent.

In one example of the silane according to Formula VIII, x=0. In anotherexample, x is 1 to 3. In another example, y=0. In still another example,y is 1 to 3. In another example, x+y=4 or x+y=2.

In some instances, R′ is represented by Formula VIII-A, x is greaterthan 0, and R₉ is nil. In other instances, R′ is represented by FormulaVIII-A and R₉ is an organic spacer. In an example, R″ is represented byFormula VIII-B and y is greater than 0. In another example, R′ isrepresented by Formula VIII-C, x is greater than 0, R₁₄ is nil and R₁₅is nil. In still another example, R′ is represented by Formula VIII-C, xis greater than 0, R₁₄ is an organic spacer and R₁₅ is an organicspacer.

When the silane includes more than one substituent represented byFormula VIII-A, the entities can be the same or different. When thesilane includes more than one substituent represented by Formula VIII-B,the entities can be the same or different. When the silane includes morethan one substituent represented by formula VIII-C, the entities can bethe same or different.

A preferred silane includes a silicon linked to one side chain thatincludes a poly(alkylene oxide) moiety and linked to three secondsubstituents. For instance, the silane can be represented by FormulaVIII with x=1, y=0 and the R′ represented by Formula VIII-A. FormulaVIII-D presents an example of the silane that includes a silicon linkedto one side chain that includes a poly(ethylene oxide) moiety, andlinked to three alkyl groups. The poly(ethylene oxide) moiety of FormulaVIII-D includes an oxygen liked directly to the silicon. Formula VIII-D:

wherein n is 1 to 15. In a preferred silane according to Formula VIII-D,n=3. Formula VIII-E presents an example of the silane that includes asilicon linked to one side chain that includes a poly(alkylene oxide)moiety, and linked to three alkyl groups. The side chain of FormulaVIII-E includes an organic spacer positioned between the silicon and thepoly(ethylene oxide) moiety. Formula VIII-E:

wherein n is 1 to 15. In a preferred silane according to Formula VIII-E,n=3. Formula VIII-F presents another example of the silane that includesa silicon linked to one side chain that includes a poly(alkylene oxide)moiety, and linked to three alkyl groups. The side chain of FormulaVIII-F includes an organic spacer positioned between the silicon and thepoly(alkylene oxide) moiety. Formula VIII-F:

wherein n is 1 to 15. In a preferred silane according to Formula VIII-F,n=3.

A preferred silane includes a silicon linked to two side chains thateach include a poly(alkylene oxide) moiety and linked to two secondsubstitutents. For instance, the silane can be represented by FormulaVIII with x=2 and y=0. One or both R′ can be represented by FormulaVIII-A. One or both R′ can be represented by Formula VIII-C. In someinstances, one R′ is represented by Formula VIII-A and one R′ isrepresented by Formula VIII-C. Formula VIII-G is an example of thesilane that includes a silicon linked to two side chains that eachinclude a poly(ethylene oxide) moiety and linked to two alkyl groups.Formula VIII-G:

wherein m is 1 to 15, n is 1 to 15 and m can be different from n or thesame as n. In a preferred silane according to Formula VIII-G, m=3 andn=3. Formula VIII-His an example of the silane that includes a siliconlinked to two side chains that each include a poly(ethylene oxide)moiety, and linked to an alkyl group, and linked to an aryl group.

Formula VIII-H:

wherein m is 1 to 15, n is 1 to 15 and m can be different from n or thesame as n. In a preferred silane according to Formula VIII-H, m=3 andn=3.

Another preferred silane includes a silicon linked to one side chainthat includes a cyclic carbonate moiety and linked to three secondsubstituents. For instance, the silane can be represented by FormulaVIII with x=0 and y=1. Formula VIII-J is a preferred example of thesilane that includes a silicon linked to a side chain that includes acyclic carbonate moiety and linked to three alkyl groups. FormulaVIII-J:

Another preferred silane includes a silicon linked to a cross link thatincludes a poly(alkylene oxide) moiety and linked to three secondsubstituents. For instance, the silane can be represented by FormulaVIII with x=1, y=0 and the R′ represented by Formula VIII-C. FormulaVIII-K is a preferred example of the silane that includes a siliconlinked to a cross link that includes a poly(alkylene oxide) moiety andlinked to three alkyl groups. The poly(alkylene oxide) moiety of FormulaVIII-K includes an oxygen liked directly to the silicon of each silane.Formula VIII-K:

wherein n is 1 to 15. In a preferred silane according to Formula VIII-K,n=4.

The electrolyte can include a single silane. Alternately, theelectrolyte can include a plurality of silanes. When the electrolyteincludes a plurality of silanes, at least one of the silanes can bechosen from those represented by Formula VIII through Formula VIII-K.Alternately, each of the silanes can be chosen from those represented byFormula VIII through Formula VIII-K. In some instances, the electrolyteincludes a silane that excludes poly(alkylene oxide) moieties and asilane that excludes cyclic carbonate moieties. For instance, theelectrolyte can include a silane that includes one or more poly(alkyleneoxide) moieties and a silane that excludes poly(alkylene oxide) moietiesmoieties. Alternately, the electrolyte can include a silane thatincludes one or more cyclic carbonate moieties and a silane thatexcludes cyclic carbonate moieties. In a preferred example, theelectrolyte includes a blend of a silane according to Formula VIII-J anda silane according to Formula VIII-F. In another preferred example, theelectrolyte includes a blend of a silane according to Formula VIII-J anda silane according to Formula VIII-D.

In some instances, the solvent includes more than one of the siloxanesor more than one of the silanes. Further, the solvent can include one ormore siloxanes combined with one or more silanes. The combination of asilane with other silanes and/or with other siloxanes can reduce theviscosity of the blended solvent. Additionally, the inventors believethat the silanes can improve the mobility of poly(alkylene oxide) inother siloxanes or silanes. Additionally, the combination of a silanewith other silanes and/or siloxanes can increase the ability of thesolvent to dissociate the salts employed in electrolyte and canaccordingly increase the concentration of free ions in the electrolyte.These features can further enhance the ionic conductivity of theelectrolytes.

The above siloxanes and silanes can be generated by employingnucleophilic substitutions, hydrosilylation and/or dehydrogenationreactions. Methods for generating the silanes and siloxanes can be foundin U.S. patent application Ser. No. 10/810,019, filed on Mar. 25, 2004,entitled “Polysiloxane for Use in Electrochemical Cells;” U.S.Provisional Patent Application Ser. No. 60/543,951, filed on Feb. 11,2004, entitled “Siloxane;” U.S. Provisional Patent Application Ser. No.60/542,017, filed on Feb. 4, 2004, entitled “Nonaqueous ElectrolyteSolvents for Electrochemical Devices,” and incorporated herein in itsentirety; and U.S. Provisional Patent Application Ser. No. 60/543,898,filed on Feb. 11, 2004, entitled “Siloxane Based Electrolytes for Use inElectrochemical Devices,” and incorporated herein in its entirety; andU.S. Provisional Patent Application Ser. No. 60/601,452, filed on Aug.13, 2004, entitled “Electrolyte Including Silane for Use inElectrochemical Devices,” and incorporated herein in its entirety.

The solvent includes one or more organic solvents in addition to the oneor more of the silanes and/or in addition to the one or more of thesiloxanes. Examples of suitable organic solvents include, but are notlimited to, cyclic carbonates such as propylene carbonate (PC), ethylenecarbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC),linear carbonates such as dimethyl carbonate (DMC), diethyl carbonate(DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC), dialkylcarbonates such as diglyme, trigylme, tetragylme, 1,2-dimethoxyethane(DME), methyl propyl carbonate, ethyl propyl carbonate, aliphaticcarboxylate esters such as methyl formate, methyl acetate and ethylpropionate, gamma.-lactones such as .gamma.-butyrolactone, linear etherssuch as 1,2-ethoxyethane (DEE) and ethoxymethoxyethane (EME), cyclicethers such as tetrahydrofuran and 2-methyltetrahydrofuran, and aproticorganic solvents such as dimethylsulfoxide, 1,3-dioxolane, formamide,acetoamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile,nitromethane, ethylmonoglyme, triester phosphate, timethoxymethane,dioxolane-derivatives, sulphorane, methylsulphorane,1,3-dimethyl-2-imidazoline, 3-methyl-2-oxazolidinone, propylenecarbonate-derivatives, tetrahydrofuran-derivatives, ethylether,1,3-propanesultone, anisole, N-methylpyrrolidone and fluorinatedcarboxylate esters. In some instances, the solvent includes acombination of two or more of the above organic solvents.

The electrolyte can optionally include one or more additives that form apassivation layer on the anode. It is believed that, in some instances,the passivation layer formed by these additives can further reducedendrite formation on anodes that contain lithium metal, lithium metalalloys and/or lithium metal intermetallic compounds. The additives canbe reduced and/or polymerize at the surface of the anode to form thepassivation layer. Vinyl ethylene carbonate (VEC) and vinyl carbonate(VC) are examples of additives that can form a passivation layer bybeing reduced and polymerizing to form a passivation layer. When theysee an electron at the surface of a carbonaceous anode, they are reducedto Li₂CO₃ and butadiene that polymerizes at the surface of the anode.Ethylene sulfite (ES) and propylene sulfite (PS) form passivation layersby mechanisms that are similar to VC and VEC. In some instances, one ormore of the additives has a reduction potential that exceeds thereduction potential of the components of the solvent. For instance, VECand VC have a reduction potential of about 2.3V vs. Li/Li⁺. Thisarrangement of reduction potentials can encourage the additive to formthe passivation layer before reduction of other electrolyte componentsand can accordingly reduce consumption of other electrolyte components.

Suitable additives include, but are not limited to, carbonates havingone or more unsaturated substituents. For instance, suitable additivesinclude unsaturated and unsubstituted cyclic carbonates such as vinylcarbonate (VC); cyclic alkylene carbonates having one or moreunsaturated substituents such as vinyl ethylene carbonate (VEC), ando-phenylene carbonate (CC, C₇H₄O₃); cyclic alkylene carbonates havingone or more halogenated alkyl substituents such as ethylene carbonatesubstituted with a trifluormethyl group (trifluoropropylene carbonate,TFPC); linear carbonates having one or more unsaturated substituentssuch as ethyl 2-propenyl ethyl carbonate (C₂H₅CO₃C₃H₅); saturated orunsaturated halogenated cyclic alkylene carbonates such asfluoroethylene carbonate (FEC) and chloroethylene carbonate (ClEC).Other suitable additives include, acetates having one or moreunsaturated substituents such as vinyl acetate (VA). Other suitableadditives include cyclic alkyl sulfites and linear sulfites. Forinstance, suitable additives include unsubstituted cyclic alkyl sulfitessuch as ethylene sulfite (ES); substituted cyclic alkylene sulfites suchas ethylene sulfite substituted with an alkyl group such as a methylgroup (propylene sulfite, PS); linear sulfites having one or more alkylsubstituents and dialkyl sulfites such as dimethyl sulfite (DMS) anddiethyl sulfite (DES). Other suitable additives includehalogenated-gamma-butyrolactones such as bromo-gamma-butyrolactone(BrGBL) and fluoro-gamma-butyrolactone (FGBL).

The additives can include or consist of one or more additives selectedfrom the group consisting of: dimethyl sulfite (DMS), diethyl sulfite(DES), bromo-gamma-butyrolactone (BrGBL), fluoro-gamma-butyrolactone(FGBL), vinyl carbonate (VC), vinyl ethylene carbonate (VEC), ethylenesulfite (ES), CC, trifluoropropylene carbonate (TFPC), 2-propenyl ethylcarbonate, fluoroethylene carbonate (FEC), chloroethylene carbonate(ClEC), vinyl acetate (VA), propylene sulfite (PS), 1,3 dimethylbutadiene, styrene carbonate, phenyl ethylene carbonate (PhEC), aromaticcarbonates, vinyl pyrrole, vinyl piperazine, vinyl piperidine, vinylpyridine, and mixtures thereof. In another example, the electrolyteincludes or consists of one or more additives selected from the groupconsisting of vinyl carbonate (VC), vinyl ethylene carbonate (VEC),ethylene sulfite (ES), propylene sulfite (PS), and phenyl ethylenecarbonate (PhEC). In a preferred example, the electrolyte includes orconsists of one or more additives selected from the group consisting ofvinyl carbonate (VC), vinyl ethylene carbonate (VEC), ethylene sulfite(ES), and propylene sulfite (PS). In another preferred example, theelectrolyte includes vinyl carbonate (VC) and/or vinyl ethylenecarbonate (VEC).

As noted, certain organoborate salts such as LiDfOB, can form apassivation layer. As a result, the desirability and/or concentration ofadditives may be reduced when organoborate are employed as salts. Insome instances, additives are employed when the solvent excludesorganoborate salts.

One example of the electrolyte includes a silane and/or a siloxane; oneor more organic solvents; one or more salts selected from a groupconsisting of LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiSbF₆, LiCF₃SO₃, LiC₆F₅SO₃,LiC(CF₃SO₂)₃, LiN(SO₂C₂F₅)₂, LiN(SO₂CF₃)₂, LiAlCl₄, LiGaCl₄, LiSCN,LiO₂, LiO₃SCF₃, LiO₂CCF₃, LiSO₆F, LiB(C₆H₅)₄, Li-methide, Li-imide andlithium alkyl fluorophosphates, and at least one anode that includes oneor more components selected from a group consisting of lithium metal, alithium metal alloy or a lithium metal intermetallic compound. In someinstances, the example solvent excludes an organoborate salt.

In some instances, the concentration of additives in the electrolytegenerally does not greatly exceed the concentration needed to form thepassivation layer. As a result, the additives are generally present insmaller concentrations than salts. A suitable concentration for anadditive in the electrolyte includes, but is not limited to,concentrations greater than 0.1 wt %, greater than 0.5 wt % and/or lessthan 5 wt %, less than 20 wt %, or less than 35 wt % where each of thewt % refers to the percentage of the total weight of solvent plusadditive. In a preferred embodiment, the concentration of the additiveis less than 3 wt % or less than 2 wt %.

The electrolyte can be a liquid. In some instances, the electrolyte is asolid or a gel. For instance, the electrolyte can include a networkpolymer that interacts with the solvent to form an interpenetratingnetwork. The interpenetrating network can serve as a mechanism forproviding a solid electrolyte or gel electrolyte. Alternately, theelectrolyte can include one or more solid polymers that are each a solidat room temperature when standing alone. The solid polymer can beemployed in conjunction with the solvent to generate an electrolyte suchas a plasticized electrolyte as a solid or as a gel. Alternately, one ormore silanes and/or one or more siloxanes in the solvent can be crosslinked to provide a solid or gel electrolyte. A polysiloxane is anexample of a cross-linkable solvent. Suitable examples for method offorming a cross linked polymer are disclosed in U.S. patent applicationSer. No. 10/810,019, filed on Mar. 25, 2004, entitled “Polysiloxane forUse in Electrochemical Cells” and incorporated herein in its entirety.

The battery can be a primary battery or a secondary battery. Further,the above cathode, anode and electrolyte combinations can be employed inother electrochemical devices such as capacitors and hybridcapacitors/batteries.

Example 1

A variety of 2032 type button cells were generated having a structureaccording to FIG. 2. The button cells include a separator 2 positionedbetween a cathode 1 and an anode 3. The anode and cathode are positionedin a chamber defined by a case 4, a gasket 5 and a cover 6. Threespacers 7 and a spring washer 8 are positioned between the anode 3 andthe case 4. The spacer 7 and spring washer 8 were made of stainlesssteel. An electrolyte positioned between the case 4 and the cover 6activates the anode and the cathode.

First cathodes were generated by mixing LiNi_(0.80)Co_(0.15)Al_(0.05)O₂(Toda Co.), a solution of PVDF in n-methylpyrolidone (NMP), andacetylene black in a mixer. The mixture was coated on an aluminumsubstrate, dried, and pressed. The resulting cathode medium was about 92wt % LiNi_(0.80)Co_(0.15)Al_(0.05)O₂, 3 wt % acetylene black, 5 wt %PVDF. Cathodes 15 mm in diameter were cut out of the result.

First anodes included a 30 μm thick lithium metal sheet on a 10 μm thickcopper substrate (Honjo Co).

A first electrolyte was prepared by mixing a first solution and a secondsolution at a volume ratio of 1:1. The first solution was generated bydissolving LiBOB to 0.8 M in a disiloxane according to formula VII withR₁=—CH₃, R₂=—CH₃, R₃=—CH₃, R₄=—CH₃, R₅=—CH₃, andR₆=—(CH₂)₃—O(CH₂CH₂O)₃CH₃. The second solution was generated bydissolving LiPF₆ to 1.2 M in a mixture of EC/DMC having a volume ratioof 1:1.

A second electrolyte was prepared by mixing a first solution and asecond solution at a volume ratio of 1:4. The first solution wasgenerated by dissolving LiBOB to 0.8 M in a disiloxane according toformula VII with R₁=—CH₃, R₂=—CH₃, R₃=—CH₃, R₄=—CH₃, R₅=—CH₃, andR₆=—(CH₂)₃—O(CH₂CH₂O)₃CH₃. The second solution was generated bydissolving LiPF₆ to 1.2 M in a mixture of EC/DMC having a volume ratioof 1:1.

A third electrolyte was prepared by mixing a first solution and a secondsolution at a volume ratio of 1:1. The first solution was generated bydissolving LiBOB to 0.8 M in a disiloxane according to formula VII-Jwith m=n=3. The second solution was generated by dissolving LiPF₆ to 1.2M in a mixture of EC/DMC having a volume ratio of 1:1.

A fourth electrolyte was prepared by mixing a first solution and asecond solution at a volume ratio of 1:1. The first solution wasgenerated by dissolving LiBOB to 0.8 M in a silane according to formulaVIII-D with n=3. The second solution was generated by dissolving LiPF₆to 1.2 M in a mixture of EC/DMC having a volume ratio of 1:1.

A fifth electrolyte was prepared by mixing a first solution and a secondsolution at a volume ratio of 1:1. The first solution was generated bydissolving LiBOB to 0.8 M in a silane according to formula VIII-E withn=3. The second solution was generated by dissolving LiPF₆ to 1.2 M in amixture of EC/DMC having a volume ratio of 1:1.

A sixth electrolyte was prepared by mixing a first solution and a secondsolution at a volume ratio of 1:1. The first solution was generated bydissolving LiBOB to 0.8 M in a polysiloxane according to formula II withR=R₁=R₃=—CH₃, R₄=R₅=R₆=—(CH₂)₃(OCH₂CH₂)₃OCH₃ and n+m+k=30. The secondsolution was generated by dissolving LiPF₆ to 1.2 M in a mixture ofEC/DMC having a volume ratio of 1:1.

A seventh electrolyte was prepared by was generated by dissolving LiPF₆to 1.2 M in a mixture of EC/DMC having a volume ratio of 1:1.

First cells were generated according to FIG. 2 with a first cathode, afirst anode, and the seventh electrolyte. Second cells were generatedaccording to FIG. 2 with a first cathode, a first anode, and the firstelectrolyte. Third cells were generated according to FIG. 2 with a firstcathode, a first anode, and the second electrolyte.

The cells were repeatedly charged and discharged between 3.0 V and 4.0V. During formation of a passivation layer in the first cycle, the cellswere charged using constant current at a rate of C/20 followed bycharging at constant voltage until the current falls to C/100. Duringthe same cycle, the cells were discharged at C/20. During the subsequentcycles, the cells were charged using constant current at a rate of C/5followed by charging at constant voltage until the current falls to C/20and were discharged at C/5. The tests were carried out at 23° C.

FIG. 3 presents the cycling data for a first cell, a second cell and athird cell as a plot of discharge capacity retention versus cyclenumber. The electrolyte in the first cell does not include anelectrolyte with a mixture of siloxane and organic solvent and shows adrop in discharge capacity retention at low cycle numbers. In contrast,the second cell and the third cell have electrolytes with a combinationof siloxane and organic solvent and show a sustained discharge capacityretention.

Other embodiments, combinations and modifications of this invention willoccur readily to those of ordinary skill in the art in view of theseteachings. Therefore, this invention is to be limited only by thefollowing claims, which include all such embodiments and modificationswhen viewed in conjunction with the above specification and accompanyingdrawings.

1. A battery, comprising: an electrolyte activating one or more anodesand one or more cathodes, the electrolyte including one or more salts ina solvent that includes one or more or more organic solvents and one ormore components selected from a group consisting of siloxanes andsilanes, and at least of the anodes including one or more componentsselected from a group consisting of lithium metal, a lithium metal alloyor a lithium metal intermetallic compound.
 2. The battery of claim 1,wherein the solvent includes a siloxane and a silane.
 3. The battery ofclaim 1, wherein at least of the anodes includes lithium metal.
 4. Thebattery of claim 1, wherein at least of the anodes consists of lithiummetal.
 5. The battery of claim 1, wherein at least of the anodesincludes a lithium metal alloy.
 6. The battery of claim 1, wherein atleast of the anodes includes a lithium metal intermetallic compound. 7.The battery of claim 1, wherein the electrolyte includes a mixture ofsalts.
 8. The battery of claim 7, wherein the electrolyte includes anorganoborate salt and a non-organoborate salt.
 9. The battery of claim1, wherein the one or more salts include an organoborate salt.
 10. Thebattery of claim 9, wherein the organoborate salt includes amono[bidentate]borate salt.
 11. The battery of claim 9, wherein theorganoborate salt includes a dihalo mono[bidentate]borate.
 12. Thebattery of claim 9, wherein the organoborate salt includes a lithiumdihalo mono[bidentate]borate.
 13. The battery of claim 9, wherein theorganoborate salt includes lithium difluoro oxalatoborate (LiDfOB). 14.The battery of claim 9, wherein the organoborate salt is represented by

wherein M⁺ is a metal ion selected from the Group I or Group IIelements; Y₃ is selected from the group consisting of —CX(CR₂)_(a)CX—,—CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—, —SO₂(CR₂)_(b)SO₂—, and—CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl, —C═NR′, CR′₃ or R′;R″ is a halogen; R′ is halogen or hydrogen; R is hydrogen, alkyl,halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to
 4. 15.The battery of claim 9, wherein the organoborate salt includes abis[bidentate]borate.
 16. The battery of claim 9, wherein theorganoborate salt includes a lithium bis[bidentate]borate.
 17. Thebattery of claim 9, wherein the organoborate salt includes lithiumbis-oxalato borate (LiBOB).
 18. The battery of claim 9, wherein theorganoborate salt is represented by

wherein M⁺ is a metal ion selected from the Group I or Group IIelements; Y₁ and Y₂ are each selected from the group consisting of—CX(CR₂)_(a)CX—, —CZZ′(CR₂)_(a)CZZ′—, —CX(CR₂)_(a)CZZ′—,—SO₂(CR₂)_(b)SO₂—, and —CO(CR₂)_(b)SO₂—; X is ═O or ═NR′, Z is alkyl,halogenated alkyl, —C═NR′, CR′₃ or R′; Z′ is alkyl, halogenated alkyl,—C═NR′, CR′₃ or R′; R′ is halogen or hydrogen; R is hydrogen, alkyl,halogenated alkyl, cyano, or halogen; a is 0 to 4 and b is 1 to
 4. 19.The battery of claim 1, wherein the one or more salts are selected froma group consisting of LiClO₄, LiBF₄, LiAsF₆, LiPF₆, LiSbF₆, LiCF₃SO₃,LiC₆F₅SO₃, LiC(CF₃SO₂)₃, LiN(SO₂C₂F₅)₂, LiN(SO₂CF₃)₂, LiAlCl₄, LiGaCl₄,LiSCN, LiO₂, LiO₃SCF₃, LiO₂CCF₃, LiSO₆F, LiB(C₆H₅)₄, Li-methide,Li-imide and lithium alkyl fluorophosphates.
 20. The battery of claim 1,wherein the electrolyte includes one or more silanes.
 21. The battery ofclaim 20, wherein at least one silane includes a silicon linked to oneor more substituents that each include a poly(alkylene oxide) moiety ora cyclic carbonate moiety.
 22. The battery of claim 20, wherein at leastone silane is represented by SiR_(4-x-y)R′_(x)R″_(y); wherein R is analkyl group, an aryl group or a halogen, R′_(x) is represented byFormula VIII-A or Formula VIII-C, R″_(y) is represented by FormulaVIII-B, x is 0 to 4, y is 0 to 4,4-x+y indicates the number of Rsubstituents, and x+y is at least 1; Formula VIII-A:

 wherein R₉ is nil or an organic spacer; R₁₀ is hydrogen; alkyl or aryl;R₁₁ is alkyl or aryl; and n is 1 to 15; Formula VIII-B:

 wherein R₁₂ is an organic spacer and p is 1 to 2; and Formula VIII-C:

 where R₁₄ is nil or a spacer; R₁₅ is nil or a spacer; R₁₆ is hydrogen,alkyl or aryl; second silane represents another silane and n is 1 to 15.23. The battery of claim 1, wherein the electrolyte includes one or moredisiloxanes.
 24. The battery of claim 23, wherein at least onedisiloxane includes a backbone with a silicon linked to one or moresubstituents that each include a poly(alkylene oxide) moiety or a cycliccarbonate moiety.
 25. The battery of claim 23, wherein at least onedisiloxane is represented by:

wherein R₁ is an alkyl group or an aryl group; R₂ is an alkyl group oran aryl group; R₃ is an alkyl group or an aryl group; R₄ is an alkylgroup or an aryl group; R₅ is represented by Formula VII-A, FormulaVII-B or Formula VII-C; R₆ is an alkyl group, an aryl group, representedby Formula VII-D, or represented by Formula VII-E; Formula VII-A:

 wherein R₉ is nil or a spacer; R₁₀ is hydrogen; alkyl or aryl; R₁₁ isalkyl or aryl; and n is 1 to 12; Formula VII-B:

 wherein R₁₂ is an organic spacer and p is 1 to 2; Formula VII-C:

 where R₁₄ is nil or a spacer; R₁₅ is nil or a spacer; R₁₆ is hydrogen,alkyl or aryl; second siloxane represents another siloxane and n is 1 to12; Formula VII-D:

 wherein R₁₇ is nil or a spacer; R₁₈ is hydrogen; alkyl or aryl; R₁₉ isalkyl or aryl; and q is 1 to 12; and Formula VII-E:

 wherein R₂₀ is an organic spacer and p is 1 to
 2. 26. The battery ofclaim 1, wherein the electrolyte includes one or more trisiloxanes. 27.The battery of claim 26, wherein at least one trisiloxane includes abackbone with three silicons, one or more of the silicons being linkedto one or more substituents that each include a poly(alkylene oxide)moiety or a cyclic carbonate moiety.
 28. The battery of claim 26,wherein at least one trisiloxane is represented by:

wherein R₁ is an alkyl group; R₂ is an alkyl group; R₃ is an alkyl groupor an aryl group; R₄ is an alkyl group or an aryl group; R₅ is an alkylgroup or an aryl group; R₆ is an alkyl group or an aryl group; R₇ isrepresented by Formula V-A or Formula V-B; R₈ is represented by FormulaV-C or Formula V-D; Formula V-A:

 wherein R₉ is nil or a spacer; R₁₀ is hydrogen; alkyl or aryl; R₁₁ isalkyl or aryl; and n is 1 to 12; Formula V-B:

 wherein R₁₂ is an organic spacer and p is 1 to 2; Formula V-C:

 wherein R₁₃ is nil or a spacer; R₁₄ is hydrogen; alkyl or aryl; R₁₅ isalkyl or aryl; and q is 1 to 12; and Formula V-D:

 wherein R₁₆ is an organic spacer and p is 1 to
 2. 29. The battery ofclaim 26, wherein at least one trisiloxane is represented by:

wherein R₁₉ is an alkyl group or an aryl group; R₂₀ is represented byFormula VI-A, Formula VI-B or Formula VI-C; Formula VI-A:

 wherein R₂₁ is an organic spacer and p is 1 to 2; Formula VI-B:

 wherein R₂₃ is hydrogen; alkyl or aryl; R₂₄ is alkyl or aryl; and r is1 to 12; and Formula VI-C:

 where R₂₅ is nil or a spacer; R₂₆ is nil or a spacer; R₂₇ is hydrogen,alkyl or aryl; second siloxane represents another siloxane and n is 1 to12.
 30. The battery of claim 1, wherein the electrolyte includes one ormore tetrasiloxanes.
 31. The battery of claim 30, wherein at least onetetrasiloxane includes a backbone with four silicons, one or more of thesilicons being linked to one or more substituents that each include apoly(alkylene oxide) moiety or a cyclic carbonate moiety.
 32. Thebattery of claim 1, wherein the electrolyte includes one or morepolysiloxanes.
 33. The battery of claim 32, wherein at least onepolysiloxane includes a backbone with five or more silicons, one or moreof the silicons being linked to one or more substituents that eachinclude a poly(alkylene oxide) moiety or a cyclic carbonate moiety. 34.The battery of claim 1, wherein the solvent includes a silane and asiloxane.
 35. The battery of claim 1, wherein at least one of the one ormore organic solvents is selected from a group consisting of cycliccarbonates, linear carbonates, dialkyl carbonates, aliphatic carboxylateesters, linear ethers, cyclic ethers, and fluorinated carboxylateesters.
 36. The battery of claim 1, wherein at least one of the one ormore organic solvents is selected from a group consisting of propylenecarbonate (PC), ethylene carbonate (EC), butylene carbonate (BC),vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate(DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC),diglyme, trigylme, tetragylme, 1,2-dimethoxyethane (DME).
 37. Thebattery of claim 1, wherein the total volume of the one or morecomponents selected from the group consisting of siloxanes and silanesis less than 50% of the solvent volume.
 38. A method of forming abattery comprising: generating an electrolyte having one or more saltsin a solvent that includes an organic solvent and a siloxane and/or asilane, and activating one or more anodes and one or more cathodes withthe electrolyte, at least of the anodes including one or more componentsselected from a group consisting of lithium metal, a lithium metal alloyand a lithium metal intermetallic compound.